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Course on requirements the programmes people world who the and Companions specific also on course provide advice assessment academic honesty protocol. of inter national education and rigorous assessment. through These programmes world to to lear ners gover nments develop challenging become who differences, is to develop who, dignity recognizing guardianship and more of their They the peaceful of encourage active, students across compassionate, understand can take the also be that the other and people, lifelong with their right. individual, responsibility consequences that groups, for their accompany and communities. own actions and the them. world. their natural to and their curiosity . conduct this in inquir y lear ning. love of the They They will seeking be are understand a concepts, global in-depth across and and willing personal and values, and appreciate grow a from and traditions communities. evaluating to histories, They range the of are their of are open to other accustomed points of view , to and experience. lives. explore and and perspectives, individuals and They lear ning cultures Caring They that creativity , IB knowledge, respect. independence Knowledgable doing, the of be: necessar y show enjoy sustained and theor y Profile shared develop skills and used research addition, and the develop young schools, people and create strive be Suggestions are extend own Inquirers and indeed, Open-minded IB profile requirements; essay , encouraged reading of issues book resources. aims approach; peaceful and programmes humanity aims caring organizations IB of whole-course Learner of lear ner inter national- statement better the IB resources; thinking. philosophy a understanding inter national The IB of knowledgable intercultural To the terms mission The IB core extended materials and understanding connections oppor tunities curriculum the of (CAS). Diploma In The range subject. Course approach wide mindedness; with Each The a These study . an of are ideas, significance. knowledge broad and and balanced and In the personal so develop range They towards positive show needs empathy , and commitment difference to compassion, feelings to of ser vice, the lives of others. and act others and respect They to have make and to a a the environment. of disciplines. Risk-takers Thinkers skills They critically approach ethical exercise and complex information than creatively to problems, in applying recognize and make thinking one and reasoned, They understand confidently and They in a and variety work and express creatively of in modes effectively and ideas strategies. Balanced more personal with willingly strong They sense of spirit are to explore brave situations forethought, and new and roles, ar ticulate and have ideas, in understand physical, well-being and for the impor tance emotional themselves of balance and to achieve others. in They give thoughtful consideration to their others. own Principled of unfamiliar and beliefs. They Reflective collaboration approach courage They their intellectual, of They with independence defending language communication. uncer tainty the and decisions. Communicators and initiative act with fair ness, integrity justice, and and honesty , respect for with the a and to lear ning and understand suppor t their experience. their They strengths lear ning and and are able to limitations personal assess in order development iii A It note is of vital on academic impor tance appropriately credit to the acknowledge owners of honesty and What constitutes is Malpractice when that information is used in your work. owners of ideas (intellectual proper ty) rights. To have an authentic in, you piece it must be based on your in individual ideas with the work of others Therefore, all assignments, oral, completed for assessment may or any student gaining an unfair one or more includes assessment plagiarism and component. collusion. is defined as the representation of the must or work of another person as your own. written The or or fully ideas acknowledged. in, and Plagiarism original results of Malpractice work, that have advantage proper ty behavior After result all, malpractice? information use following are some of the ways to avoid your plagiarism: own language and expression. Where sources are ● used or referred to, whether in the form of Words and suppor t quotation or paraphrase, such sources ideas of another person used to direct must one’s arguments must be be acknowledged. appropriately acknowledged. ● How of I acknowledge the work way used the that you ideas footnotes that are enclosed within quoted verbatim quotation marks must be and acknowledged. others? The of do Passages of acknowledge other and people that is you ● have through the CD-ROMs, Inter net, use be bibliographies. email and treated in any the messages, other same web sites electronic way as on media books the must and jour nals. (placed Footnotes endnotes be (placed provided another at when at the you document, or information provided do to not that is need par t of do are the par t of resources “Formal” in need means you that a or of a page) document) paraphrase summarize for be are to as used you in a formal your ● is, they should of work. accepted forms of use one presentation. Works involves separating the into different categories newspaper ar ticles, be is of CDs and works of information as to how a allowing that work can find the same is compulsor y your takes the place, malpractice by includes: work assessment duplicating and to be copied or submitted by another student work for different assessment and/or diploma requirements. reader or viewer information. the forms of malpractice include any action providing gives you an unfair advantage or affects the of of another student. Examples include, A extended unauthorized material into an examination essay . room, misconduct falsifying iv This work suppor ting dance, where Inter net-based ar t) in as a film, work. books, taking bibliography of par t own be you results your a your and graphs, must the that full music, ar ts, defined student. not visual acknowledged. Other resources, are whether or components magazines, they data, material This resources (e.g. if maps, programs, similar must Collusion ● use and use for usually photographs, computer ar t, ar ts, all creative another of of theatre ● several of acknowledged Y ou list sources audio-visual, knowledge. include The illustrations, the That footnoted ● from information knowledge”. to or document. footnote of should that of another a assumed Bi bliographies the end closely “body not bottom quote provide a definitions the a CAS during record. an examination, and About The new Level is syllabus for thoroughly chapter the the is divided following book Mathematics covered into in lesson this size Standard where book. designed Each sections a GDC to analytical with skills applications Exploration and concludes Theory of you Historical exploration know? is instrument and teaching not a that usefulness developed has is most has in powerful, both other mathematics and learning stopped beauty in as a about its developing own The in since area years ago using the included of and it which Course Companion will prior then. guide you latest topics curriculum and emphasis is improved and in their the new with internal placed on the understanding real problem life full solving and coverage of development as critical well Companion denotes as suitable for About Laurie the Buchanan Denver, leader examination has Colorado and a for on Paper One and over teaching 20 years. examiner an She is also a part of the proficiency Fensom assistant workshop curriculum courses for has Mathematics School in been nearly 35 that and Kemp Programme currently Inter national assistant that different are to Casio Where using Similar the solutions interactive an examination work FX-9860GII ebook suppor t, to the examples shown. complete GDC also order. accompanying a student is of the are CD text, interactive and papers, ideas for the inter nal exploration. education The life-long is a growing, contextual, enables ever technology students to become learners. US spelling has been used, with IB style for terms. for is a in team the IB curriculum workshop He is He at developer for board and is an online IB. mathematics and for La Rondie has has been teaching IB Diploma Paper mathematics at Sevenoaks School for worked years. He has been an assistant examiner and team. IB is mathematics Inter national assistant and leader an IA workshop for both papers moderator. curriculum currently Nexus an review review He board developer for in has and Mathematics ser ved is an on the SL IB online IB. examiner Stevens has been teaching IB Diploma HL. has been teaching mathematics the and there and suppor t, Programme Edward page would mathematics She leader teaching years. Singapore. every those examiner review Coordinator Mathematics and The Jill for but a approach adaptable, team Jim into application teacher Plus entity . integrated 10 as ethics integrated TOK solutions the Programme Two. the sample changing concepts Paul SL through authors been principal practice a calculator Mathematics and thinking. questions the mathematical be is follow lear ning, Note: Course confidence all The mathematical application strengthen through assessment. of for TI-84 assessment the clearly are chapter. includes glossar y , The build sequence to TI-Nspire study Sumerians recognized 5,000 are each appropriate valuable disciplines. difficulty , Internationalism, there possible through flexibility Mathematics in Questions Knowledge It Did and used. suggestions section tip be increase understanding. features: Investigations Examiner's may head of School examiner for 20 IB years. mathematics in for Thailand. 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Mathematics ser ved been College mathematics the reader Board IB and AP in Trinity She SL, a is an Calculus School, assistant workshop curriculum table High leader review . for leader Jill the exam. v Contents Chapter Functions 1.1 Introducing 1.2 The functions domain Cartesian and Function 1.4 Composite 1.5 Inverse 1.6 Transforming range 4 of a relation on plane 1.3 Chapter notation functions functions functions Quadratic functions a Solving quadratic 2.2 The 2.3 Roots 2.4 Graphs 2.5 Applications quadratic of equations Patter ns 6.2 Arithmetic 13 6.3 Geometric 14 6.4 Sigma 16 6.5 Arithmetic 21 6.6 Geometric 6.7 Convergent 6.8 Applications 6.9 Pascal’s of quadratic of and (Σ) and sequences 162 sequences 164 sequences notation arithmetic 167 and series 170 series 172 series 175 series of and sums geometric to infinity 178 and patter ns triangle 181 and the binomial expansion 38 equations sequences 6.1 34 formula quadratic Patterns, series 2.1 8 and equations Chapter 184 41 functions quadratics 43 Chapter 53 7.1 Limi ts Limits and and derivatives convergence 196 n Chapter Probabi li ty 3.1 Definitions 64 3.2 Venn 68 3.3 Sample diagrams product space 3.4 Conditional 3.5 Probability Chapter diagrams and the r ule probability tree diagrams Exponential and Exponents Solving 4.3 Exponential 4.4 Proper ties 4.5 Logarithmic 4.6 Laws 4.7 Exponential 4.8 Applications of exponential logarithms functions logarithms logarithmic Chapter equations and of functions Rational 5.1 Reciprocals 5.2 The 5.3 Rational reciprocal functions function functions 7.4 The chain line for and derivative of x 200 derivatives r ule and higher 208 order derivatives Rates 7.6 The 85 7.7 More of 215 change derivative on and and extrema motion in a line 221 graphing and 230 optimization problems Chapter 240 Descriptive 8.1 Univariate analysis 103 8.2 Presenting data 107 8.3 Measures of 109 8.4 Measures of 115 8.5 Cumulative 118 8.6 Variance equations 127 and Chapter statistics 256 257 central tendency 260 dispersion 267 frequency and standard 271 deviation 276 Integration 9.1 Antiderivatives 9.2 More 131 and the indefinite integral 291 on and indefinite 9.3 Area 142 9.4 Fundamental 143 9.5 Area 147 9.6 Volume of 9.7 Definite integrals other vi r ules 122 logarithmic exponential tangent 7.5 logari thmic functions of More 77 4.2 The 7.3 89 functions 4.1 7.2 definite between integrals 297 integrals Theorem two of 302 Calculus cur ves 313 revolution problems with 309 318 linear motion and 321 Chapter Bivariate 10.1 Scatter 10.2 The 10.3 Least 10.4 Measuring analysis diagrams line of best squares fit regression correlation Chapter 334 15.1 Random 15.2 The binomial 345 15.3 The normal Right-angled triangle 11.2 Applications of trigonometr y right-angled Using the 363 triangle trigonometr y 11.3 369 coordinate variables axes in 16.1 About 16.2 Inter nal the 16.3 How 16.4 Academic the Record 16.6 Choosing 11.4 The sine 380 16.7 Getting 11.5 The cosine 11.6 Area 11.7 Radians, Chapter r ule r ule Vectors: triangle 12.2 Addition and 12.3 Scalar 12.4 Vector 12.5 Application Chapter and basic 391 of of the 13.3 Trigonometric 13.4 Graphing 13.5 Translations of a line unit using the circle and 568 Chapter Using a graphic calculator display 1 Functions 2 Differential 3 Integral 4 Vectors 5 Statistics 572 calculus calculus 598 606 608 and probability 612 stretches sine with Prior learning Number 633 2 Algebra 657 448 3 Geometr y 673 454 4 Statistics 699 Chapter Practice papers Practice paper 1 708 469 Practice paper 2 712 478 Answers 483 Index sine and functions Calculus 1 of functions with Chapter 462 functions transformations star ted 456 functions and Chapter unit identities Combined Modeling 564 420 437 circle circular cosine 563 topic 430 functions equations trigonometric cosine vectors vectors Circular Solving keeping a 562 562 426 equation Using marked Honesty 557 407 subtraction 13.2 13.7 sectors concepts 13.1 13.6 389 product 556 criteria is 386 Vectors 12.1 538 exploration exploration 16.5 arcs 527 Exploration assessment 373 a 520 distribution distribution The trigonometr y of distri butions 349 Trigonometry 11.1 Probabi li ty 339 Chapter Chapter wi th trigonometric functions 14.1 Derivatives 14.2 More 14.3 Integral 14.4 Revisiting of practice of trigonometric functions withderivatives sine and linear cosine motion 496 500 505 510 vii What's The as on material well as lear ning. help you The a your wealth On to on the these of whole print CD-ROM other two succeed CD? in resources pages your text is includes you entire specifically can see Mathematics presented the as what written you Standard a student will to as an suppor t find Level user-friendly book and eBook, your how it will course. eBook Extra menu for content or use can attached This in be to the and A Go range out is Contents and to found and in specic icon there is page or the home. Contents in the extra straightforward Menu, at pages. appears wherever Navigation class either through book content. the through Search tools. of tools to annotate enables you pages to with zoom your in and own notes. The glossar y coverage explains making viii of provides the tricky it a comprehensive language of terminolog y. powerful the It revision is subject fully tool. Extension and editable chapter material containing exercises solutions and to is a included variety activities. this of Full material for each extra wor ked are also provided. CASIO 9860-GII Practice paper 2 Simultaneous and quadratic equations 1.5 Tolerance Asian Solving simultaneous linear equations European Low 30 Medium 50 40 High 40 20 80 Practice paper 2 Practice prepare exam for solutions papers your can will help examinations. be found on the you to fully Worked website www.oxfordsecondar y.co.uk/ibmathsl Powerpoint worked in the presentations solutions book, providing for showing hints and the cover Alternative GDC the given book 9860-GII be is instructions for for the calculators, so supported no matter TI-84 you can what all Plus material and be sure calculator in Casio- you you will use. detailed practice common Using a graphic display calculator papers errors and tips. ( , 0) 0 (3, 0) What's on the website? V isit www.oxfordsecondar y.co.uk/ ibmathsl worked for free access solutions question in the to to each Course the and full ever y Companion. www.oxfordsecondar y.co.uk/ibmathsl also offers activities suppor t you for your a the range of TI-Nspire GDC to help understanding. Functions CHAPTER OBJECTIVES: 2.1 Functions: 2.2 Graphs of domain, range, functions, by composite, hand and identity using GDC, and inverse their functions maxima and minima, −1 asymptotes, the T ransformations 2.3 graph of of f (x) graphs, translations, reections, stretches and composite transformations Before Y ou 1 you should Plot e.g. start know how to: coordinates. Plot Skills 1 y a 2 the check Plot these A(1, 3), points B(5, −3), on a coordinate C(4, 4), plane. D(−3, 2), D C 1 points A(4, 0), B(0, −3), E(2, −3), F(0, 3). y A C(−1, 1) and 0 D(2, 1) –2 x 1 –1 3 2 b 4 Write down 2 the A –1 on a coordinate plane. coordinates –2 1.5 of E H B –3 points A to 1 H –4 0.5 2 Substitute e.g. values into an expression. D C B 0 Given x = 2, y = 3 and z = −5, –2 x –1 1 2 3 0.5 2 find the value of a 4x + 2y y b − 3z –1 4x a + 2y = 4(2) + 2(3) = 8 + 6 = G 14 –0.5 2 y b 2 − 3z = (3) −3(−5) = 9 + 15 = 24 F –2 3 Solve linear equations. 2 e.g. Solve 6 4x 6 − 4x = Given that x = 4, y = 6 and z = −10, find 0 2 a − = 0 ⇒ 6 = 4x + 3y z b − 3y y c − z d 4x 3 1.5 = x ⇒ x = 1.5 Solve y 6 4 Use your GDC to a 3x − 6 = 6 5x b + 7 = −3 c graph 4 a function. 4 Graph these functions on your GDC 2 e.g. Graph f (x) = within 0 –6 2x − 1, –3 ≤ x ≤ –4 –2 the given domain. Then x 2 4 6 3 sketch the functions on paper. –4 a y = 2x b y = 10 − 3, −4 ≤ x ≤ 7 –6 − 2x, −2 ≤ x ≤ 5 –8 2 5 Expand e.g. linear Expand (x binomials. + 3) (x − 2) c 5 y = x – 3, –3 ≤ x ≤ 3. Expand 2 = x + x Functions − 6 a (x + 4) (x + 5) c (x + 5) (x − 4) b (x − 1) (x − 3) The Inter national Space Station (ISS) has been orbiting the Ear th [ International Space Station over 15 have times actually difficult as it a day seen for it? might more than Spotting seem – ten the years, ISS provided with you yet the know how many naked in eye which of is us not as direction –1 to of look. the heads. ‘stars’, Although lowest the orbits Thanks which to ISS travels possible, its makes large it at solar fairly at a speed of approximately 390 wings of easy to it is one , 7.7 km s distinguish km the as it it is above in one our brightest moves across One the night of the rst sky . mathematicians to The relation gives the speed of the ISS, where t is the time study the concept of function measured in hours and d is the distance traveled in was kilometres. philosopher This is a mathematical relationship called a function and is just of how a mathematical function can be used to describe (1323–1382). a He situation. worked this with independent dependent In Nicole one Oresme example chapter you will explore functions and how French they can and variable be quantities. applied to a wide variety of mathematical situations. Chapter . Introducing Investigation In some hands 1 countries with How b Copy – is ever ybody handshake, a it many and if functions there handshakes customar y in the are 3 handshakes complete Number people are this at business meeting. If there there there for are 4 meetings are 3 2 to people shake there handshakes and is so on. people? table. Number of Y ou of people might nd it helps handshakes to tr y this out with a 2 group 3 in of your friends class. 4 5 6 7 8 Do not join the points 9 in this case as we 10 are dealing with c the Plot points on a Car tesian coordinate plane with the whole number numbers. of people Write d a the formula number of Relations Distance on x-axis for people, and (m) and the the number number of T ime The (s) 200 34 300 60 400 88 way ➔ A There of and is showing data is nothing provided In other that Functions in a a table time within set of it shows takes words, order. brackets all any numbers cer tain is (400, 88). ordered at r un information and specific special these this (300, 60) enclosed relation relation. of (200, 34), pieces comma H, in the terms y-axis. of the the for a amount student 15 to two handshakes, on n of (100, 15), handshakes functions 100 Another of as ordered pairs: Each They in distances. the are ordered separated form pair by a (x, y). pairs. about group come the of in numbers numbers pairs. that is a are in relation a has only (discrete) ➔ The is domain ordered pairs. domain of the set of all the first numbers (x-values) of the The The the ordered pairs above is {100, 200, 300, curly mean ➔ The range is the set of the second numbers brackets, { }, 400}. ( y-values) in 'the set of'. each pair. The range of Example Find the the ordered pairs above is {15, 34, 60, 88}. domain a {(1, 4), (2, 7), b {(−2, 4), and range (3, 10), (−1, 1), of these relations. (4, 13)} (0, 0), (1, 1), (2, 4)} Answers a b The domain is The range {4, The The is domain range is is {1, 2, 7, 10, {−2, {0, 1, 3, −1, 4} First 13} 0, 1, 2} 4} elements Second elements Do repeat not there are ordered ➔ A of function the element be a is a domain of the function mathematical of the range no two of the is pairs in ordered the values 4s such and that associated function. ordered two the pairs ordered even two pairs though 1s in the pairs. relation function in In may each with order have for the element exactly a one relation same to first element. Example Which of these sets of ordered pairs a {(1, 4), (2, 6), (3, 8), (3, 9), (4, 10)} b {(1, 3), (2, 5), (3, 7), (4, 9), (5, 11)} c {(−2, 1), (−1, 1), (0, 2), (1, 4), are functions? (2, 6)} Answers a Not a function number 3 because occurs twice the in the domain. b A function; elements c A function; elements all are all are of the first different. of the first different. Note some that of it the doesn’t matter y-values are that the same. Chapter Exercise 1 2 Which A of these sets a {(5, 5), b {(−3, 4), c {(4, 1), d {(−1, 1), (0, 3), e {(−4, 4), (−4, 5), f {(1, 2), For each whether (4, 4), (3, 3), (−1, 6), (4, 2), (2, 2), ordered (2, 2), (0, 5), (4, 3), (2, −1), relation is a (2, 8)} (−2, 8)} (5, 2)} the domain and range and say function. y a functions? (3, −1)} (−3, 7), (4, 2), identify are (4, 5)} (1, 7), (−3, 6), (3, 2), pairs (1, 1)} (4, 4), (1, 6), diagram, the of y b 2 2 Write down the 1 1 coordinates x 0 1 2 3 as x 0 1 –1 2 ordered 3 pairs. 4 –1 3 Look it back takes for between The a at a can Y ou can relation student line represent use is a table distance vertical Y ou the the on to r un traveled 4 that cer tain and shows the distances. time taken a Is amount the of time relationship function? test relations ver tical function page or and line not, test by functions to on a determine drawing Car tesian whether ver tical lines a plane. par ticular across the Car tesian graph. and the plane ➔ A relation intersect line is the a function graph if more any than ver tical once. line This drawn is called will not after the vertical René test Example Which of a coordinates Car tesian are named Frenchman Descar tes (1596 – 1650). these relations y are functions? b y y c y = |x| 0 0 x 0 { Functions x x Continued on next page Answers a y b c y y Crosses 0 a A function Exercise 1 0 x Which A b x x 0 function Not c a twice function B of these relations a are functions? b y c y y Draw, or 3 imagine, 2 ver tical 1 lines 0 x x 0 x on the –1 graph. d e y f y If the a ‘solid function has y 2 indicates 1 value x 0 dot’ 0 x 0 is •, that this the included in x 2 the function. –1 If the function has a –2 ‘hollow dot’ , this ° indicates value the g y h is that not the included in function. i y y 3 2 1 0 x 1 –1 –2 2 3 4 5 2 2 1 1 0 –4 –3 –2 x 0 –1 x 1 –1 –1 –2 –2 Chapter Use 2 your GDC to sketch these straight line graphs. Indicate a y = x e Are f Will y b = x + 2 y c = 2x − 3 y d = x- they all all functions? straight lines Explain be your functions? and /or the region y < 3x − 2. Is this a function? 2 Use not an a algebraic method to show that x of view y = on a and Cartesian range on your sketch. of your your GDC, graph aim near to the have the corners of window. 4 is T ry domain the 2 + function. The y-axis using substituting values . crosses Why? the 4 line Why? ends Sketch the answer. When 3 where 4 a of positive and negative x. relation plane R Y ou can often write the domain and range of a relation using A inter val notation. This is another method of writing down a set of D O M A I N G numbers. For example, for the set of numbers that are all less than 3, E you can write the inequality x < 3, where x is a number in the set. [ In inter val Inter val notation, notation this uses set only of numbers five is written (–∞, 3) A function domain x-values) symbols. range maps the (horizontal, onto the (vertical, y-values) Brackets ( ) Square [ ] brackets How Innity many numbers ∞ are Negative innity −∞ Union there in sequence 3, ∪ 4,… if the 0, we 1, 2, go on forever? How To use inter val are ➔ Use the round many brackets ( , ) if the value is not included in there as point Use (a in (–∞, hole the or square 3) or when the asymptote, brackets [ , ] or if graph a is undefined at in the the sequence graph numbers notation: 0, 0.5, 1, that 1.5, 2, 4,… if 2.5, 3, 3.5, jump). the value is par t of the we go on graph. forever? Whenever the point. there Then Put a For example If graph a (−∞. union If break on on 3) in the another between (–∞, goes a write sign goes it is ∪ values, inter val each write for inter val to the the inter val values ‘join’ after them up to that point. together. (4, ∞) forever to the left, forever to the right the domain then the (x-values) domain starts ends with with ∞). Why If a graph travels downward forever, the range (y-values) star ts do we with undened? (−∞. And Usually the x- or we a graph use y-axis. numbers. if For Functions goes inter val forever, notation However, example, up in you to can inter val then the describe use it to a range set of describe notation x ≥ 6 is ends with values any along group [6, ∞). ∞). of call innity y Asymptotes 8 Asymptotes are visible on your GDC for some functions. An 1 6 y asymptote is a line that a graph approaches, but does not example, in the graph of y = x 2 1 For , the line approaches x x 0 –6 the x-axis will The not (y = 0), actually x-axis or y but never reach = 0 is y = touches 0, callled but the = 4 intersect. it. will As we always horizontal go get to infinity closer and the 2 4 line closer. asymptote. –8 The y-axis There on will or x be rational = a 0 is the more ver tical in-depth asymptote treatment of for the same asymptotes reasons. in the chapter functions. F inding asymptotes looking at is called the by graph locating asymptotes by inspection. Example Identify the horizontal and ver tical asymptotes for 2x x these functions if they exist. + 2 x a y = 2 y b = y c x = ( +1 x ) ( +1 x 2 ) Answers y a 4 Horizontal As 3 asymptote y = we go along the x-axis to the 0 left the cur ve gets closer but never 2 actually meets the x-axis. 1 0 –2.5 –2 –1.5 –1 –0.5 x 0.5 1 1.5 2 2.5 y b 8 Horizontal 6 asymptote y = 2 4 Ver tical 2 x = asympote –1 x –3 –2 –1 1 2 4 –8 y c 6 Horizontal 4 asymptote 2 Ver tical x 0 –2 –1 = –1 y = 0 asympote and x = 2 x 2 4 –4 Chapter Exercise Identify they C the horizontal and ver tical asympotes 3 functions, if 4 x = 3 y 2 = y 3 = x 2x y 4 these exist. y 1 for x 2x = y 5 +1 +1 = y 6 = 2 x Set In + 2 x builder set builder x 1 9 notation notation we use curly brackets { } and variables to Y ou express the domain and range. We can compile sets of to using inequality and other may wish inequalities explore the symbols. ‘internationalism’ of the set of { symbols the less than in } language of < mathematics. less than or greater than greater than is a equal to ≤ > or member of equal the to set ≥ of real numbers ∈ ➔ Set notation: { x : x > 6 } Inter val often notation considered efcient The set of x-values such that x is less than Set Description builder Around notation notation are +∞) x is greater than –2 {x : x > the 4] x is less x lies than or equal to 4 {x : x ≤ 3) between including (–∞, 5) ∪ [6, x +∞) is less than or −3 −3 but than 5 equal to and not or 3 {x : −3 ≤ x < 3} 3 for greater {x : x < 5, x ≥ 6} +∞) x may be any real also also How called people brackets’ than. x > 2, For to use show ‘backwards greater number example: and ] Functions ∞, −4[ ] 2, is ∞ square than [ is or less equivalent equivalent to x < Radicals called does this x ∈ nd some examples? Some same surds. affect understanding? you (–∞, the Brackets parentheses. are 6 to −4. there 4} are [−3, world different −2} symbol. (–∞, more set notation many words (–2, than 6 builder Inter val is Can more Example Y ou Find the domain and range of this may wish to function. explore the inuence y of technology on 2.5 notation and 2 vice versa. 1.5 1 0.5 0 –4 –3 –2 x –1 1 2 3 4 Answer The {x : domain x The { y : ≥ −4} range y ≥ of or of 0} [–4, the or Example the [0, function is x +∞) only equal function is The +∞) takes to values than or −4. function greater greater than only or takes equal to y-values 0. What Find the domain and range of each values included y a are function. b in the domain y 0 ≤ x ≤ 1? 4 2 How many values are 3 1 there? 2 0 x 1 –1 –2 x 0 1 –1 –3 –4 Do we all use the Answers same a The domain and 0 is {x : −2 ≤ x < notation mathematics? < x ≤ [−2, −1) ∪ an range is {y : −4 < y ≤ (−4, that The domain ∈ of the function is x can take any real or (–∞, range ≥ −1 is have notations of −3} to +∞). the function or [–3, the same is thing. {y : y = Different value. represent The to 1]. different x x included. countries b are dot 1} not or empty (0, 3]. indicate The We 3} using or in −1 Fur thermore, +∞). different teachers from same the countr y use different notations! Chapter Exercise 1 Look D back numbers a 2 to of the 4 at the handshakes function? Find page If so, domain a what and graph for is various the range and formula numbers domain for the each and of the people. Is this range? these b y of for relations. c y E 4 4 3 3 2 2 y 1 0.5 1 1 F x 0 –4 –3 –2 –1 1 2 3 0 x 0 4 1 2 3 –1 6 5 x –0.5 0.5 1 y d e f 6 y 4 4 2 2 –2 –4 0 x 0 –6 2 y 4 x 0 x –2 –2 –2 –1 –4 –6 g h y i y y 5 5 4 4 3 3 1 0 x 2 1 1 1 0 –2 –1 0 x 1 –5 2 –4 x –3 1 3 4 5 –1 –2 –2 –3 –3 –4 Exam-Style 3 Use your Question GDC to sketch these graphs. Y our Write down the domain and range of GDC will nd the x- and y-intercepts. T o do each. this algebraically, use the fact that a function 2 a y = 2x − 3 b y = x crosses 2 c y = x x-axis when y = 0 and crosses the 3 + 5x + 6 d y = f x – 4 y-axis e the when x = 0. For example, the function y = 2x − 4 crosses the x-axis where 2x − 4 = 0, x g h y = j x = 2. It e crosses the y-axis where y = 2(0) − i 3k k l Functions gives a most unusual answer . carefully for a hole where x = −3. Look 4 = −4. . Function Functions equation are y = function the as 2x f f (x) = notation often 2x + described 1 describes symbol + ➔ f (x) is (x) can also 1 ‘f and read as be ‘f ’ we so y of x’ written by y write = equations. as a For function this of equation example, x. in By the giving function the notation f (x). and like means this: f : the x → value 2x + of function f at x. 1. f An ordered Finding pair f (x) function f for at Example (x, y) a can be par ticular that written value as of x (x, : (x) → 2x + 1 means evaluating that f is a that maps function the x to f (x) 1. German mathematician Evaluate If + the function f (x) = 2x + 1 at x = = philosopher x + 4x − 3, find f i (2) f ii and 3. 2 b 2x value. The a means f (x)). (0) iii f (−3) iv f (x + Gottfried 1) Leibniz rst used mathematical the term Answers a f (3) = 2(3) + 1 = ‘function’ 7 For x, substitute in 1673. 3. 2 b f i (2) = (2) + 4(2) – 3 = 4 + 8 − 3 = 9 2 ii f (0) iii f (−3) = iv f (x (0) + 4(0) – 3 = 0 + 0 − 3 = −3 2 = = (−3) 9 − + 12 4(−3) − 3= – 3 −6 2 + 1) = (x + 1) + 4(x + 1) – 3 + 4 − 2 = x = x + 2x + 1 + 4x 3 2 Exercise + 6x + 2 E 1 Find f (7) i ii f (−3) f iii ( ) iv f (0) f (a) v for these functions. a f (x) = x − 2 f (x) b = 3x c f (x) = x 2 d f (x) = 2x + 5 f (x) e = x + 2 2 2 If a f (x) = x – 4, find f (−a) b f (a + 5) e f (5 − a) c f (a − 1) 2 d f (a − 2) Notice Exam-Style 3 If g (x) = that we do not Question 4x − 5 and h (x) = a find x when g (x) = 3 b find x when h (x) = −15 c find x when g (x) = 7 – always use letter for the 2x Here g h (x). f we and h. a have of used When considering terms function. velocity time we in often 4 a If h (x) = find b Is there a use h (−3). v(t). value where h (x) does not exist? Explain. Chapter The 5 volume of a cube with edges of length x is Y ou can use mathematical functions 3 given by the function f (x) = x to a Find f (5). b Explain represent For what f (5) represents. example, pizzas the number from suppose family of watch. the eats football If life. number depends games of on you eat 3 pizzas you during ever y football g (6) i g (−2) ii g (0) iii game, the function ‘number of pizzas’ (p) ‘number of football = 3 would be times g iv games’ (g) or p = 3g. Can you think of another Evaluate b real-life g (1) i g (1.5) ii g (1.9) iii g (1.999) v What do d Is e Graph there when you a x = Exam-Style notice value the of x about for function 2. the It amount could of on your which your answers g (x) GDC does and to b? not look the number talking on the of minutes you spend phone. what happens Explain. The of a par ticle is given by v (t) = initial a Find the initial b Find the velocity after 4 c Find the velocity after 10 d At − 9 m s . star t, does at the par ticle when t = 0. seconds. come to par ticle comes when v = 0. find Extension material Worksheet 1 on CD: f a . A (2 + h) Composite composi te one function ➔ f b The the written as is a result composition of f (g (x)), + h) functions function to (3 combination of of two functions. Y ou function is apply another. the function which is read f with as ‘f of the g of x’, or g ( f g)(x), ° which When you another For is read as evaluate variable example, if for f (x) ‘f a composed function with f (x), you 2x + 3 then f (5) 2 Y ou can find 2 ➔ A 1) = 2(x + 1) by substituting + 1) and + 3 = 2x function is defined + Functions substitute a number or = 2(5) + 3 = 13 x + 1 for x to get 5 applies by ( f one g)(x) ° x’. 2 composi te another of 2 2 + f (x f (x g x. = to rest? rest velocity seconds. The time the velocity . the what velocity −1 t means be spend Question velocity Given you exist? 2 The perhaps money g (1.9999) vi or c function? g (1.99) iv about 8 own Evaluate a 7 your 6 your things function = f ( g(x)). to the result of - Polynomials Example 2 If f (x) = 5 − 3x and g (x) = x + 4, find (f g)(x). ° g (x) goes in here Answer 2 2 (f g)(x) = 5 – 3(x = 5 – 3x + Substitute 4) x + 4 into f (x). ° 2 – 12 2 = Y ou may value of −3x need – 7 to evaluate a composite function for a par ticular x. Example 2 f (x) = 5 − 3x and g (x) = x + 4. Find (f g)(3). ° Answer Method 1 2 (f g)(x) = 5 – 3(x + Work 4) out the composite function. ° 2 = −3x – 7 2 (f g)(3) = –3(3) – = −27 7 = −34 7 Then ° – substitute 3 for x. Both Method methods give 2 the same result – you 2 g (3) f = (13) (3) = 5 + – Example 4 = 13 3(13) = −34 Substitute 3 into Substitute that g (x). value can into f (x). use the one you prefer . 2 Given a (f f (x) = 2x + 1 and g)(x) g (x) (f b = x – 2, find g)(4) ° ° Answers 2 2 a (f g)(x) = 2(x – 2) + Substitute 1 x – 2 into f (x). Or ° use Method 2: 2 = 2x − 2 3 g (4) and = (4) – 2 = 14 then 2 b (f g)(4) = 2(4) – 3 = 29 Substitute ° Exercise 4 for x. f (14) = 2(14) + 1 = 29 F 2 1 Given a ( f f (x) = g)(3) 3x, g (x) b = ( f ° e ( g f ( f )(4) f h (x) c = j n )(5) )(2) find g)(–6) d ( f g ( g k f ( f o )(–6) h ( g )(x) l (h f )(x) ° h)(x) ° f ° h)(x) ( g g)(x) ° ° g)(3) ° 2, ° f (h + ° f (h x ( f ° h)(3) ° and ° h)(2) ( g 1 g)(0) ( g ° m + ° ° i x p (h (f ° h)(2) ≠ (h ° f)(2) g)(x) ° Chapter 2 Given 2 f (x) ( g a f = x − )(1) 1 and ( g b f ° = 3 − )(2) x, find ( g c f ° ( g e g (x) f )(3) ( f f g)(–4) ° ( f g ( f d g)(3) ° g)(x ° Exam-Style )(4) ° + 1) ( f h ° g)(x + 2) ° Questions 2 Given 3 the ( f a functions g)(x) f (x) = ( f b x and g (x) = x + 2 find g)(3) ° ° 2 Given 4 ( a the f functions g )(x) f (x) ( g b ° = f 5x and g (x) = x + 1 find )(x) ° 2 g (x) 5 = x + Find a 3 ( g and h (x) = x – 4 ‘Hence’ h)(x). means ‘Use the work to preceding ° Find b (h g)(x). obtain the ° Hence c solve the equation ( g h)(x) = (h ° required g)(x). result’. ° 2 If 6 r (x) = x – 4 and s (x) = x , find (r s)(x) and state its domain ° and . range. Inverse functions –1 ➔ The inverse of that function. a function If f (x) = 3x − 4 and g (x) f (x) is f (x). It reverses the action of = , then f (10) = 3(10) – 4 = 26 and g ( 26) = = 10, so we are back to (f ° g) (10) = 10 where So g (x) Not If g all we all is star ted. is the inverse functions the inverse values in the of have f (x). an inverse. function domain of of f f, −1 Note then and f g will will reverse also be the the action inverse of of f that the inverse the ‘–1’ is ➔ and g are Functions ( f inverse f (x) g)(x) and functions, g (x) are we write inverses of g (x) one = f (x). another if: = x for all of the x-values in the domain of g = x for all of the x-values in the domain of f. ° ( g f )(x) ° The ➔ horizontal Y ou can use line the test horizontal line test to identity inverse functions. If a horizontal once, there Functions is line no crosses inverse the graph function. of a function of not f; an g. exponent f means for −1 When f more than (power). Example Which of these functions have a inverse functions? y b 5 5 4 4 3 3 2 2 1 1 0 0 –3 –2 x x –1 1 2 1 3 3 –1 –2 –3 –4 –5 y c y d 3 2 2 1 1 x 0 2 1 3 4 5 6 x 7 –1 –1 –2 –2 –3 –4 Answers a y b y 5 5 4 4 3 2 2 1 1 –3 –2 0 –1 2 1 3 x –3 4 you Wafa 0 x –4 Did know Buzjani, that a mathematician Abul Persian from 1 –1 the No inverse 10th centur y, used function functions? There is –3 a crater on the moon –4 named –5 Inverse y c after him. function y d 3 3 2 2 1 1 0 x 1 2 3 4 5 6 x 7 1 –2 –3 Inverse function No inverse function Chapter The ➔ graphs The graph function Here are of of in some inverse the the inverse line y examples = of functions of a function is a reflection of that x functions and their inverse y = functions. x y y y 1 f (x) y = y x f (x) x 1 –1 f = (x) f (x) x f (x) x x f (x) −1 If (x, y) lies function in the on in line the y Exercise 1 Use the have the = line line x y f (x), = x becomes then (y, ‘swaps’ point x x) lies and y, on so f (x). the Reflecting point (1, 3) the reflected (3, 1). G horizontal inverse line test to determine which of these functions functions. y y a b Pioneering 7 Indian 6 6 5 5 in the scientist 6th included 4 3 2 2 1 1 0 –5 –4 –3 –2 x 0 –1 –6 –3 –2 –1 x 1 2 3 4 –1 –2 a –3 c d y y 3 2 2 1 x 0 1 Functions 2 3 4 work by 7 5 6 x 0 Panini centur y BCE functions. 2 Copy the graphs line = and y x a of the these graph functions. of the For inverse each, the y b y draw function. c y 10 8 8 8 6 6 6 4 4 4 2 2 0 x 0 0 x x 4 2 –2 –2 –2 –4 –4 –4 –6 –6 –6 –8 –8 –10 y d e y f y 8 6 8 4 4 6 2 4 x 0 –4 2 –4 0 –1 x 1 2 3 4 –2 x –3 –2 –1 0 1 2 3 –4 Finding Look x on at inverse how the the functions function f (x) = 3x 3x form inverse – 2 is made up. We star t with left. x To algebraically the inverse function we – 2 reverse the process, using operations. The x + inverse of +2 is 2 2 x The 3 So inverse of ×3 is ÷3 The next example Example shows you how to do this without diagrams. –1 If f (x) = 3x – 2, find the inverse function f (x). Answer y = 3x – 2 x = 3y – 2 Replace f (x) Replace ever y ever y x + 2 = y = y with with x y. with y and x. 3y Make x y the subject. + 2 3 x 1 f (x ) + 2 1 Replace = y with f (x). 3 Chapter As you saw function in the line swapped ➔ To in of a y x = x, and find and the and functions f is ‘swaps’ then inverse for of function which y, the solve Example graphs given the x and made function y and their reflection y. the So in inverses, of the the graph Example 12 y inverse = f (x) we subject. algebraically , replace f (x) with y y −1 If f (x) = 4 − 3x, find f (x) Answer x − y = 4 − 3x x = 4 − 3y = −3y 4 x Replace f (x) Replace ever y with with x y. with y and ever y y x. 4 Make = y the subject. y 3 4 y x = 3 4 x 1 f (x ) –1 = Replace y with f (x). 3 To check the that the inverse function Example 13 is correct, combine (f f –1 So in functions −1 )(x) = x and f and f are inverses of each other. ° ➔ The It function leaves x I (x) = x is called the identity function. unchanged. −1 So f = f I ° Exercise H Exam-Style 1 If f (x) Question = and g (x) = 2x – 4, ii f find a g (1) i and ( f g)(1) (–3) and ( g f ° ( f iii g)(x) iv ( g ° b 2 What Find the )(–3) ° f )(x) ° does this inverse tell for you each about of functions f these and g? functions. 3 a f (x) = 3x − 1 b g (x) = x – 2 c h (x) = x + 5 + 3 d f (x) = e g (x) = Self-inverse 3 – 2 f h (x) = 2x functions are g such h function Look –1 is f (x) f (x) = 1 – x b f (x) = x c f (x) Functions for functions = are its the same. self-inverse if a and inverse What a 3 that in question 3. –1 Evaluate 4 f (5) where f a (x) = 6 – x f b (x) = f c (x) = Note of If 5 f (x) that point image (a, –b) after a –1 = , find f (x). reection the in the line y Exam-Style = x is the point Question (b, –a). x 6 Draw a the plotting Draw b graph several the line of f (x) = 2 by making a table of values and points. y = x on the same graph. –1 c Draw the in line the graph y = of f by reflecting the graph of f x. –1 State d the domain and range of f and f 2 The 7 the function square Find By this f (x) root = x has no inverse function function. does have However, an inverse function. inverse. comparing the range and domain explain why the inverse 2 of Prove 8 never . that be is the not the graphs a as f (x) linear = x function and its inverse can per pendicular. Investigation 1 of Transforming Y ou same should Sketch use y = your x, y = – + material Worksheet 1 the same to 1, y sketch = x − all 4, y the = x graphs + in this 4 will also and on 2 effect the contrast y = −2x y 3 = + Compare What x 3, y Compare = the of + y and effect Sketch do graphs Sketch your y 3, = constant = y x = + 2x 0.5x + contrast does |x|, and effect y = |x + terms does graphs of y = + 3 3, on your 2|, y your changing 2 4 Sketch y Compare = x , and |x + = −x equation written as have y = mx + b y = mx + c or y = the 3x + 3, same The axes. is functions. the = x-coefcient |x − 3| on have? the same coefcient the number of x that multiplies the x-value. |x| the modulus axes. means functions. the values of h have x. See chapter 18 on more explanation. h|? 2 y line b? changing contrast (number) a for the this functions. of What nd axes. of What CD: investigation. standard Compare on Polynomials functions Y ou on - functions GDC x Extension 2 , contrast y = 2x your What effect does the What effect does changing , 2 y = 0.5x on the same axes. functions. negative sign have on the graph? 2 the value of a have on the graphs of y = ax ? Chapter In the 1, 2 investigation and 3 changed. by were The all you the graphs should same in have shape par t 4 found but should the that your position have been graphs of the in par ts graphs reflected or changed stretching. These look are at examples these of ‘transformations’ transformations in of graphs. We will now detail. Translations Shift ➔ f upward (x) + k downward translates ver tically units or a f (x) distance ➔ of k f (x) – k translates ver tically upward. units y a f (x) distance of k downward. y 3 3 f (x) + 1 2 2 f (x) 1 1 f (x) x –2 –1 x –2 –1 1 2 1 3 –1 3 f (x) Shift ➔ to f (x the + k) right or k left, > when k f (x) units to ➔ the f (x − right, y translates when k k f (x) units > to the 0. y 3 2 2 f (x) f (x) 1 + k) horizontally 0. 3 f (x 1 left translates horizontally – 1 2) x –1 1 2 x 3 –1 1 3 4 5 –1 f (x – 2) Translations can be represented by vectors in the form is the horizontal component and b is the vertical where a T ry component. transforming some functions different is a horizontal shift of 2 units units by the ver tical shift of on right, Functions and a denotes vector the a down. to is ver tical a horizontal shift of 2 units values right. Translation 3 down. shift of 3units your GDC. with of k Reflections Reflection ➔ −f (x) in the x-axis reflects f (x) Reflection in the ➔ f (−x) x-axis. in the y-axis reflects f (x) in the y-axis. y y 3 3 f (x) 2 f (x) 1 x 0 –2 –1 1 2 x 3 –3 –2 –1 1 f (x) 2 3 f (–x) Stretches Horizontal stretch (or compress) Ver tical stretch (or compress) A ➔ f (qx) stretches or ➔ compresses pf (x) stretches f stretch factor f (x) horizontally with ver tically scale with 0 factor p scale < p < 1 will actually p. compress y a where scale factor with (x) the graph. y f (2x) f (x) 3 3 2 2 1 1 2f (x) 0 –3 –2 x –1 1 2 x 3 –2 –1 –1 1 3 –1 f (x) Students make The transformation is a horizontal The transformation is often mistakes a vertical with stretches. stretch of scale stretch factor of scale factor p It When When q > 1 the graph towards the 0 < q < 1 the 1 away graph Example 1 Given sketch a f (x from graph the the impor tant stretches to from remember 0 < p < the x-axis. different 1 the graph for towards the effects of, is is compressed stretched the y-axis When When > is away compressed p is example, 2f (x) x-axis. and y-axis. f (2x). the the + graph of graphs 1) b f the function f (x) shown y here, of: (x) 4 − 2 c f (−x) d −f (x) e 2f (x) 3 2 f (x) 1 x 0 1 { 2 3 4 Continued 5 on 6 next Chapter page Answers y a b y c y 4 4 2 3 3 1 f f (x) – (–x) 2 2 2 0 f (x + 1) x 1 2 3 4 5 6 1 1 –1 –2 x –1 1 0 2 3 Translated to the 4 one –6 unit Translated two units down –5 –4 –3 Reflected –2 in –1 0 the y-axis left y d x 5 y e 1 12 10 0 x 2 1 3 4 5 6 8 –1 6 –2 f (x) 2f (x) –3 4 –4 2 x 0 1 Reflected Supply and and in the demand economics Supply are and x-axis cur ves in Ver tical business reections. Radioactive 3 2 4 stretch decay 5 of 6 scale cur ves factor 2 are reections. demand y 6 Demand Supply y Number of 5 100 smota P Surplus 4 P * fo ECIRP 3 Equilibrium rebmuN 2 Shor tage 1 Q * 75 50 25 x 0 10 20 30 40 QUANTITY 50 Number parent of atoms 0 60 x 1 2 3 4 5 6 Q Number of half lives y Exercise I f (x) 4 Exam-Style 1 Copy the Question graph. Draw 2 these functions on the same axes. –6 a f (x) + d f (x g f (2x) + 4 b f (x) 3) e f (x – − 2 c 4) f –2 f (x) x 0 2 4 6 –2 2f (x) –4 y g f (x) q 4 2 Functions g, h and q are transformations of f (x). 2 Write each transformation in terms of f (x). h 0 –10 –8 –6 –4 –2 –2 –4 Functions x 2 4 6 8 10 3 Functions Write q, each s and t are transformations transformation in terms of of y f (x). f (x). 6 t f (x) s 4 q 2 x 0 –10 –8 –6 2 4 6 8 –2 Exam-Style 4 Copy the Question graph of f (x). Sketch the graph of each of y these 3 functions, and state the domain and range for each. f (x) 2 a 2f (x – 5) 1 f (2x) b + 3 0 x 2 –1 –2 5 The graph of f (x) is shown. A is the point y (1, 1). 5 Make separate copies of the graph and draw the 4 function after each On graph, transformation. 3 each label the new position of A as A 2 1 A a f (x + c f (–x) 1) b f (x) + d 2f (x) 1 1 0 –4 e f (x − 2) + x 1 2 3 4 5 3 –4 –5 6 In each change case, the describe graph of the f (x) 3 a f (x) = x transformation into f (x) = x c f (x) = x, Exam-Style 7 Let f (x) = graph of would g (x). 3 , g (x) = −(x , g (x) = (x ) 2 b the that 2 g (x) = − −2x 3) + 5 Question 2x + If 1. in a Draw b Let the graph of f (x) for 0 ≤ x ≤ a domain the = f (x + 3) – 2. On the same graph draw −3 ≤ x ≤ you only draw the g (x) function for given 2. must g (x) is question, for that −1. domain. Review exercise ✗ 1 a If g (a) = 4a − 5, find g (a − 2). b If h (x) = , find h (1 − x). 2 2 a Evaluate f (x − 3) when f (x) = 2x − 3x +1. 2 b For f (x) = function 2x + 7 defined and by g (x) ( f = 1 − x , find the composite g)(x). ° Chapter 3 Find the inverses a f (x) of these functions. = 3 b g (x) = 2x + 3 4 Find the inverse of f (x) = . Then graph the function and 5 its Find inverse. the inverse functions for a 6 f (x) Copy = 3x each a + 5 b graph and draw the inverse of each function. b y y 4 3 3 2 2 1 1 x 0 x 1 –2 –1 0 1 2 3 –1 –2 –3 –4 7 Find the domain and range for a each of these graphs. b y y 10 7.5 5 2.5 5 x –2 6 7 –2.5 0 x –5 5 –1 –5 –7.5 Exam-Style 8 For each given a Question function, write combination f (x) = x, of reflected a single equation to represent the transformations. in the y-axis, stretched ver tically by a factor of 2, horizontally by a factor and of translated 3 units left and 2 units up. 2 b f (x) = x , reflected in the x-axis, stretched ver tically by a factor , of horizontally by a factor of 3, translated 5 units right 9 and a Explain b Graph 1 how the Exam-Style unit to down. draw inverse of the f (x) inverse = 2x + of a function from its graph. 3. Question 3 10 Let f (x) = 2x + 3 and g (x) = 3x – 2. −1 a Find g (0). b Find ( f g)(0). ° Functions c Find f (x). Exam-Style y Questions 4 11 The graph shows the function f (x), for −2 ≤ x ≤ 4. 3 a Let h (x) b Let g (x) = f (−x). Sketch the graph of h (x). = f (x − 1). The point A(3, 2) on the graph of f is 1 transformed to the point P on the graph of g. 0 –3 Find 12 The and a the coordinates functions g (x) Find = x an f + and g of are defined as f (x) = 3x The 2. for x –1 instruction ‘Obtain expression –2 1 2 3 4 5 P ( f g) using (x). the ‘Show required information that…’ result given) means (possibly without the ° −1 b Show that f −1 (12) + g (12) = formality 14. For of ‘Show proof ’. that’ questions you do not 13 Let g (x) = 2x – 1, h (x) = a Find an expression for ≠ usually need A method to use a calculator . (h g) (x). Simplify good is to cover up the your ° right-hand side then out of the equation and answer. b Solve the equation (h g) (x) = work the left-hand side until 0. ° your answer hand Review 1 Use your and the same as the right- exercise GDC range is side. of to sketch 2 Sketch the function 3 Sketch the function the function and state the domain y = (x + 1)(x − 3) and state its domain and range. 1 y and = x Exam-Style state its domain and range. + 2 Questions 4 The function f (x) is defined as a Sketch b Use the your and the cur ve GDC f (x) to for help −3 ≤ you x ≤ write ≠ −. 2. down the value of the x-intercept y-intercept. 5 a Sketch the graph of b For what c State the value of domain x is and f (x) undefined? range 6 Given the function write b sketch down c write the the Let f (x) down = a Sketch b Solve 2 − the x both f (x) equations of the asymptotes function coordinates 2 7 f (x). a of = of the intercepts with both axes. 2 and g (x) functions = x on − 2. one graph with −3 ≤ x ≤ 3. g (x). Chapter Exam-Style Questions 3 8 Let f (x) = x – 3. −1 a Find the inverse function f (x). −1 b Sketch c Solve both f (x) and f (x) on the same axes. –1 f (x) 9 = 10 the Consider cur ve the ≠ Sketch (x). f of f (x) functions for f −5 and g ≤ x ≤ 2, where including f (x) = 3x – any 2 asymptotes. and g (x) = x – 3. −1 a Find the inverse function, f −1 b Given that g −1 (x) = x + 3, find ( g f )(x). ° When −1 c Show that (f g)(x) IB exams = . ° have words in bold –1 d Solve script, –1 ( f g)(x) = ( g f ° you Let it means that )(x) ° must do exactly , x ≠ 2. what is required. For example d Sketch the graph of h for −6 ≤ x ≤ 10 and −4 ≤ y ≤ any Write down CHAPTER the equations 1 Introducing ● A ● The domain ● The range ● A function ● A relation than The once. Use is ● is is Set set the the is is a a of ordered set set of of all the relation function This but given not as 3. asymptotes. is and pairs. the if called any the range first second where round brackets square at that ( , ) if point brackets [ , ] numbers numbers ever y vertical of x-value ver tical a line line (x-values) (y-values) is related drawn of in will the each to a not ordered pairs. pair. unique y-value. intersect the graph more test relation on a Cartesian plane if the (a value hole the is not included or asymptote, value is included or in in a the graph or when the graph jump). the graph. notation: : The set of x-values x < 6 } such that x is less than 6 Continued as just notation: undefined Use 3 SUMMARY a domain Interval of the = functions is relation be asymptotes. x e equation 10, could including the Functions on next page Function ● f (x) is notation read as Composite ● The as ‘ f of and means ‘the value of function f at x’. functions composition f (g (x)), x’ which of is the function read as ‘f of f g with of the x’, or function ( f g)(x), g is written which is read as ° ‘f ● A composed with composi te another and g of x’. applies function is defined by ( f one g)(x) function = to the result of f ( g(x)). ° Inverse functions −1 ● The the ● of inverse a function f (x) is f (x). It reverses the action of function. Functions f (x) ( f xfor g)(x) = and all g (x) of are the inverses x-values of in one the another domain if: of gand ° ( g f )(x) = x for Y ou can use all of the x-values in the domain of f. ° ● horizontal inverse The ● in line graph the ● To ● The line find horizontal crosses a line test function to identify more than inverse once, functions. there is If a no function. graphs The the of of y the inverse the = inverse of a function is a reflection of that function x. inverse function functions I(x) function = x is algebraically , called the replace f (x) identity function. with It y and leaves x solve for y. unchanged. −1 So f f = I ° Transformations of functions ● f (x) + ● f (x) – ● f (x + k) translates f (x) horizontally k units to the left, ● f (x − k) translates f (x) horizontally k units to the right, ● −f (x) ● f (−x) ● f (qx) stretches f (x) horizontally with scale factor ● pf (x) stretches f (x) ver tically ktranslates k translates f (x) f (x) ver tically ver tically reflects f (x) in the x-axis. reflects f (x) in the y-axis. a a distance distance of k of k units units upward. downward. where k where > k 0. > 0. with scale factor p. 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Chapter Quadratic functions and equations CHAPTER OBJECTIVES: 2 the 2.4 quadratic y-intercepts, The form x function axis ↦ a(x of − f (x) = ax + bx + c = 0: its graph, its ver tex, x- and symmetr y p)(x − q), x-intercepts (p, 0) and (q, O) 2 The form x ↦ a(x − h) + k, ver tex (h, k) 2 2.7 solving 2.7 the quadratic 2.7 the discriminant 2.8 applications Before Y ou 1 of the form ax + bx + c = 0 and the graphing nature skills of and roots solving equations to real-life situations start know simple equations formula of you should Solve quadratic how equations to: for a Skills given 1 variable. check Solve a each 3a – 5 equation. = a + 7 2 e.g. 3b Solve − 2 = for b: 0 b 4x + c 3(n – 1 = 4) = 21 5(n +2) 2 3b = 2, b 3 2 e.g. Solve the equation n + 3 = 5. 2 n + 3 = = 2, 5 2 n 2 n = Factorize ± 2 mathematical expressions. 2 Factorize 2 e.g. Factorize p each expression. 2 – 5p: a 2k − b 14a 10k 3 p(p – 5) 2 + 21a − 49a 2 e.g. Factorize the expression c 2x + 4xy − 10a + 3x + 6y ab + 2b 2 ax – 3x + 2a – 6: d 5a − 2 x(a – 3) + 2(a – 3) e n f 2x + g m 4n + 3 2 (x + 2)(a – 3) − x − 3 2 2 e.g. Factorize the expression x – 3x – − 36 10: 2 h (x + 2)(x – 5) 2 e.g. (2a Factorize + 5)(2a – the expression 5) Quadratic functions and equations 4a – 25: 25x 2 − 81y This World War Washington spray This water of DC. in picture drinking the Memorial The fountain parabolas, cur ved water in paths a opened at the these they 2004 in Memorial from trajector y . streams can in trajectories. streaming similar of and was fountains beautiful shows cur ved called II be of a simple The shapes water modeled are by 2 mathematical Functions Other In like these situations functions the functions this which include height of a the you that form called area will functions the can dropped chapter, quadratic are of modeled a object study are (x) = quadratic be of f figure over how given +bx ax +c. functions by and quadratic measuring time. to in graph standard 2 form, f (x) = ax + bx + c; tur ning point form, 2 y f = a(x (x) in = − h) a(x their − own + k; p)(x way . maximum height you use to might find area, the the and − q). If of the factorized Each you a of these wanted spray of factorized of form a to be If are useful the from form. rectangle would forms know water tur ning-point dimensions form, a fountain, you with a wanted par ticular helpful. Chapter . Solving quadratic equations Some 2 An equation that can be written in the form ax + bx + c = of equations 0, written where a ≠ 0, is called a quadratic equation . These are these in are the not form all 2 ax examples of quadratic they 2 – x + 4x + 7 = bx + c = 0, but equations: can be rearranged 0 into this form. In quadratic 2 = 5x 2x(3x (x – 3x – – 7) 7)(2 2 = – 0 5x) = a trinomial 14x 2 2 ax In this section, you will begin solving quadratic + bx Before by you the term, bx is ➔ xy solve This = quadratic equations by term, and (x to 0, understand then proper ty − the linear x = 0 can or be y an = a)(x − b) = 0, impor tant x − This a 0 proper ty sometimes to: = is the term. proper ty: 0. expanded then c factorizing, the If is factorization impor tant If ax quadratic is constant it c, equations. called Solving + or x − b = zero is called product 0. property. Example Solve these equations by factorization. 2 a x 2 − 5x − 14 = 0 b 3x 2 + 2x − 5 = 0 c 4x + 4x the left-hand + 1 = 0 Answers Factorize 2 a x − (x − 5x − 7)(x x − 7 x = 7 = x = −2 14 + 0 = 2) = or or the expression on side of the equation. 0 0 x + 2 x = −2 = 0 Set each factor equal to zero, using the zero product proper ty. 7 2 b 3x + (3x 3x + + 2x − 5)(x 5 = 5 – = 1) 0 Factorize 0 = Set 0 or x – x = 1 = 0 the expression factor equal to on the left-hand side of the equation. zero. You can also find the solutions with your GDC. (See Chapter 17 Section 1.7.) 5 x each = 1 3 5 x = , 1 3 2 c 4x + 4x + (2x + 1)(2x (2x + 1) 1 = + 0 1) = When 0 there we will get be the same only one factor twice, solution. 2 = 0 equation has two equal roots. 1 2x + 1 = 0 x = − GDC help on CD: Alternative 2 demonstrations Plus and GDCs Quadratic functions and equations Casio are on for the TI-84 FX-9860GII the CD. We it is a ‘perfect sometimes say square’ that and this Exercise In this your 1 A exercise, answers Solve by solve with all your the equations − 3x + 2 = 0 − Solve + 25 by = 0 x e + − 56 = 0 m c − 2x − 48 6c − = 0 b f + 2 5x − 4 = 0 b + 30 = 0 6b + 9 = 0 2 5c + 8 = 0 2h c 2 4x 11m factorization. + 2 d a 2 2 6x a check 2 a b 2 x then factorization. 2 2 and 2 x d hand’ GDC. 2 a ‘by − 16x − 9 = 0 e − 3h + x − 5 = 0 2 3t + 14t + 8 = 0 6x f − 12 = 0 2 If a quadratic you will shown have in to is not rearrange Example Example Solve equation written the terms in the before form ax you can + bx + c factorize = 0, as 2. these equations by factorization. 2 8x a − 5 = 10x − 2 x (x − 5 = 10x − 2 Collect − 10x − = 0 equation. b + 10) = 4(x − 2) Answers 2 8x a like ter ms on one side of the 2 8x (4x + 4 x + 1)(2x 1 = 3 − 0 3) or = 2x 0 − = and solve for x. 0 3 1 x Factorize 3 = x = 2 4 Ancient 1 x Babylonians 3 = or and 4 Egyptians quadratic x(x b + 10) = 4(x − 2) Expand the brackets and collect like + 10x = 4x – 8 of + 6x + 8 = these 0 Factorize and solve for years 4)(x + 2) = ago for example, 0 solutions x + 4 = 0 or x + 2 = to = −4 x = = −4, Exercise 1 Solve factorization. 2 2x − 7 = 13 + x 2 b 2n + 11n d 2(a − 5)(a = 3n − n − 4 Use 2 3z(z c + 4) = −(z + 9) + 5) = + 5 = f 2x x number Exam-style 3 The x + two 2 The number , equation and to write solve 2x and its square differ by 12. Find the x number. question per pendicular and represent 1 for A to 1 an 2 ‘x’ 21a the x 36 x e of B by + area rectangle. −2 2 x a the −2 a x problems 0 concerning x to x. nd, (x + thousands ter ms. 2 x equations like 2 x studied 2 5x – sides of a right-angled triangle have lengths 3. hypotenuse has length 4x + 1. Find x. Chapter Investigation Solve these – equations perfect by x 3 x 2 + 10x + 25 = 0 2 x + 14x + 49 = 0 4 x 2 − What 18x do original a are 0 by Describe + 9 8x + 16 = − 20x 0 = 0 using any + patterns 100 you = 0 see in the equations. these with are equations methods your three called completing other x 6 polynomial think quadratic without = notice? is you Solving there 81 quadratic do Some + you trinomial Why 6x − 2 x A + 2 2 5 trinomials factorization. 2 1 square ‘perfect the cannot you can terms. square trinomials’? square be use solved to by solve factorization, a quadratic but equation GDC. 2 Consider above. the The equation left side of x + this 14x + 49 equation = is 0 a from the perfect investigation square, because it 2 has two identical factors: 2 + x 14x + 49 = (x + 7)(x + 7) = (x + 7) 2 To solve the equation x + 14x + 49 = 0, you could factorize, which 2 would give the equation (x + 7) = 0, and lead to the answer x = −7. 2 What If if you you were collect all asked the to terms solve on the one equation x side of the + 14x + equation, 49 = you 5? get 2 x + get 14x an + 44 exact Example ✗ Solve = 0, which answer, does however, not as in easily . Y ou Example could still 3. each equation without using the 2 a factorize shown GDC. 2 x + 14x + 49 = 5 b x – 6x + 9 = 6 Answers 2 a x + 14x + 49 = 5 Factorize the perfect square trinomial 2 (x + 7) = 5 on the Take x + 7 = ± 5 the left the hand side of the equation. square root of both sides of equation. Leaving x has two solutions: −7 + 5 in x = −7 ± 5 −7 − your radical (surd) 5 form gives 2 b x – 6x − 3) + 9 = 6 Again, we see that the left side of 2 (x x x − 3 = = 3 ± = ± 6 the is a perfect trinomial, so we method in par t x 3 equation can square use the same 6 6 Quadratic functions and equations has answers and as two 6 a solutions: 3 + 6 and solutions. the exact In Example Y ou can equation, ➔ T o the using add a the perfect Example Solve equations perfect complete and a 3, use square method the square called square, result to take both trinomial perfect half the of the any the square equation. side of each the equation by completing the + of x, This square step it, creates equation. square. 2 x trinomials. quadratic coefficient the left square solve completing sides on to 2 a involved trinomials 10x = 6 x b 2 – 12x = 3 x c – 3x – 1 = 0 Answers 2 a x The + 10x = 6 + 10x + 25 coefficient of x is 10. Halve this 2 x = 6 + (5) 25 and square it (25). 2 (x x + 5) + 5 = = ± Complete 31 both 31 Solve x = −5 ± x – 12x = The 3 x – 12x + 36 = 3 + 12 36 2 for adding 25 to x. coefficient − 6) = ÷ 2 − 6 = ± = 6, Complete 39 Solve x by of x is 12. Over one thousand 2 2 (x square 31 2 b the sides. for 6 the = 36 years square. Hindu x. were ago, = and mathematicians developing 39 methods x Arab 6 ± similar to 39 completing the square 2 x c – 3x – 1 = Add 0 1 to both sides of the equation. to 2 solve quadratic 2 x – 3x = 1 3 ⎛ Half 9 of 3 is , ⎝ − 3x + 9 equations. 4 nding They were is ⎜ 2 x ⎞ and 2 9 3 ⎟ 2 ⎠ solutions = 1 + 4 4 9 Add to to both sides of the mathematical equation. 2 3 ⎞ ⎛ 4 13 x problems 2 Solve 4 ⎠ for x. ‘What must square 3 ± x = Exercise completing the its This amounts is written to as + 10x = 39. square. 2 + 8x = 3 x 2 − 5x = 3 + 7x − 4 + x 2 − 6x + 1 = 0 x 4 2 x of C 2 5 when 10 2 2 x roots, 39?’ x 3 by 13 2 x the 2 own by which, increased 3 ± x be 13 = 2 1 as ⎟ ⎝ Solve such = ⎜ = 0 2 − 2x − 6 = 0 x 6 − 3 = 0 2 ➔ In order to complete the square, the coefficient of the x term 2 must be 1. If completing divide the the through x term square, by the has you a coefficient can factor out other the than 1, before coefficient, or coefficient. Chapter Example Abu Solve each equation by completing 2 2x a the + 8x = 6 b 3x Kamil (c.850 – Shuja square. 2 15x = – c.930), also 2 known Answers as al-Misri, al-Hasib meaning 'the 2 2x a + 8x = Divide 6 both sides of the equation by calculator from Egypt', 2 2 x + 4x = 3 x + 4x + 4 (x + 2) the coefficient of x , which is 2. was one of the rst to 2 = 3 + Use 4 completing the square to introduce symbols 2 = solve 7 for x. for indices, m x + 2 = x = –2 x 7 ± n x such as m+n = x , in algebra. 7 ± 2 4x b − 20x = 5 2 4(x − 5x) = Divide 5 through by the coefficient 2 5 of 2 x – 5x x , which is 4. = 4 25 5 25 2 x – 5x = + + 2 4 4 4 5 Half of 5 is , and 2 5 ⎞ ⎛ 30 x 15 = ⎜ 2 ⎞ ⎜ ⎟ ⎝ 2 25 is . 4 ⎠ = ⎟ 2 ⎝ 4 ⎠ 5 2 15 x = ± 2 2 This 5 x ⎛ 5 = answer could also be written as 15 ± x 2 ± 30 = 2 2 Exercise Solve by D completing the square. 2 1 2x 3 5x 5 2x 2 + 12x = 6 − 10x + 2 − x 2 3x 4 4x 6 10x 2 Y ou 6x = 3 + 6x − 5 2 = 0 2 . − = 0 2 − The know 6 = 0 quadratic that a quadratic + 4x − 5 = 0 formula equation can be written in the form 2 ax + bx + equation Y ou c = 0. using would Suppose the you wanted completing the to solve square this general quadratic method. have: Subtract c from both 2 + ax bx + c = 0 sides of the equation. 2 ax + bx = –c Divide c b both sides of 2 x + x = – a a the 2 b ⎛ 2 x + x b = ⎜ a ⎝ ⎠ ⎛ b ⎞ + − ⎟ 2a by a 2 c ⎞ + equation ⎜ a ⎝ ⎟ 2a ⎠ b Half of b is a . 2a 2 b Squaring this gives 2 4a Quadratic functions and equations 2 2 b ⎛ x c ⎞ + = ⎜ b − + ⎟ 2a ⎝ 2 a ⎠ 4a 2 2 b ⎛ x b ⎞ + 4 ac = ⎜ ⎟ 2a ⎝ 2 4a ⎠ 2 b x 2 b + = 4 ac ± ± b − 4 ac = 2 2a 2a 4a 2 −b x ± b − 4 ac = 2a This gives solve ➔ any The us an extremely quadratic quadratic useful formula which can be used to equation. This formula 2 For any equation in the form ax + bx + c = in 0, for 2 −b x ± b formula the is Formula the IB given booklet exam, so − 4 ac = you do not have to 2a memorize Example Solve each equation using the 2 a quadratic formula. 2 x + it. 4x − 6 − 6 = 0 = 0 b 2x 2 − 3x = 7 3x c = 7x + 6 Answers 2 a x + 4x 2 −4 x ± 4 − 4 2 4 ± x ( 1) ( Use the a 1, quadratic for mula with 6) = = b = 4, and c = −6. (1) 40 This = answer is cor rect, but it can still 2 be 4 ± 2 x simplified. 10 = = − 2 ± 10 2 2 b 2x − 3x = 7 − 3x − 7 ( 3) First write for m ax the equation in standard 2 2x = 2 0 + bx + c = 0 2 3 ± x 4 2 3 ± x ( 2) ( 7) Use the a 2, quadratic for mula with = (2) = b = −3, and c = −7. 65 = 4 2 c 3x = 7x + First 6 write the equation in standard 2 2 3x − 7x − 6 = for m 0 2 7 ± x ( 7 4 ) 2 7 ± x ( 3) ( = Use the a 3, + bx + c quadratic = 0 for mula with 6) = b = −7, and c = −6. (3) 121 = ax 7 ± 11 = 6 6 2 x = − , 3 3 Chapter Exercise Solve each E equation using the quadratic 2 1 4x 3 5x 5 x 7 2x 2 + 9x − 7 = 0 2 3x + 6x + 1 = 0 4 x 6 3x 8 2x 2 + 2x − 8 = 0 2 − 2 6x = −4 2 = x − 3 2 3x = 1 x – 2x = 9 10x = 9x = 5 sum Find x 2 x + 1 of the 4 = 5x Example + + 3 10 x The + 2 − 6 9 formula. the two squares of two consecutive integers is 613. integers. Answer First, 2 + (x 2 + 1) = need to write an equation. 613 2 x + x + 2x + 1 = Let 613 2 2x + 2x − 612 = x 0 like + x − 306 = be the consecutive 2 x you 2 x smaller integer. integer, and Expand the x + 1 be brackets the and next collect ter ms. 0 Divide by 2. 2 (1) −1 ± x − 4 ( 1) ( This −1 ± x 1225 = factorization (1) equation = or −18 The or two Two Find Since 17 −18 and −17, or 17 and 18. There are are for two two x have a sum of 50 and a product of 576. numbers. rectangle has Find the length Find the value 4x x + – a perimeter and of x width in the of 70 the m 6 6 Quadratic functions and equations and an rectangle. diagram. 3x of area of 264 m + be solved using square. values . for x, there will also be 1. possible F numbers the are there values 2 3 also 2 integers Exercise A the −1 ± 35 two 2 could completing = 2 1 quadratic = 2 x −306 ) pairs of consecutive integers. Exam-Style 4 Questions A rectangle If the has length is a length of decreased 23 cm by x and cm, a and width the of width 16 cm. is increased 2 by x cm, the dimensions area of of the the new new rectangle is 378 cm . Find the rectangle. 2 5 The formula of ball a ball . in t h = 2 + seconds the 14t after – it 4.9t is gives thrown. the For height, how h metres, long is the air? Roots of quadratic Extension material Worksheet 2 Solve 1 these – roots equations using 8x + these 16 = 0 4x b equations Solve 3 5x – these 14 = 0 equations What 4 3x let’s + 6 patterns questions Now + 9 = formula. 0 quadratic 25x c 8x the + 2 = , take = 0 did 2x b you and another ? Why look at 10x + 1 = 0 quadratic 5x c – 3x – 4 = 0 formula. 2 – notice + formula. 0 2 + quadratics 2 – using 2 x a quadratic 12x the 3x b CD: equations 2 + on more 2 – using 2 x a quadratic 2 – Solve 2 of the 2 x a Two equations challenging Investigation - in do 4x the you the + 5 = 0 solutions think this quadratic 4x c of the + 2x + 1 equations = 0 in happened? formula, used for 2 solving and c equations are all in the form ax + bx + c = 0, where a, b, constants. 2 −b x ± b − 4 ac = 2a This par t formula of the the give quadratic information us will about solution. all the formula, the The us roots roots the of an discriminant of a quadratic discriminant , equation, is the par t will without of the equation. give One us actually giving quadratic 2 formula the under symbol ‘△’ the to radical (square represent the root) sign, b – 4ac. We often use discriminant. 2 ➔ For a quadratic equation ax + bx + c = 0, 2 ● if b – 4ac > 0, the equation will have two different real 2 if b equal – 4ac = 0, the equation will have two equal real if b think – 4ac < 0, the equation will have no real with roots of an two as having roots only 2 ● can equation roots ● Y ou one solution. roots. Chapter Example Use the discriminant to determine the nature of the roots of each equation 2 a 9x + 6x + 1 = 0 1 = 0 4 b 3x – 5 = x Answers 2 a 9x + 6x + This a = is 9, a b quadratic = 6 and c equation = with 1. 2 △ = 6 The – 4(9)(1) equation equal = 36 will − 36 have = Calculate 0 the discriminant. Discriminant two = 0 means two equal roots. roots. 4 b 3x – 5 = First, get for m. Multiply the equation into standard x by x on both sides, 2 3x – 5x = 4 then add 4. 2 3x – 5x – 4 = 0 2 Remember, △ = b – 4ac. 2 △ = (−5) = 25 The − + 4(3)(−4) 48 = equation different Example real 73 will △ have > 0 means two dif ferent real roots. two roots. 2 Find two the value(s) different of real k for which the equation 2x – kx + 3 = 0 will have roots. Answer Solution: For the equation to have two dif ferent 2 b – 4ac > 0 real roots, you must have △ > 0. 2 (–k) – 4(2)(3) > 0 2 k – 24 > 0 2 k > You 24 can use the absolute value For when |k| > |k| > taking the square root in more on value, see Chapter inequality. k > Exercise 1 Find roots 6 2 6 2 or Section k < –2 6 G the for value each of the discriminant, x c 4x 5x – 3 = 0 b 2x + 5 = 0 d x + the nature 4x + 1 = 0 16 = 0 2 – x + 2 x state 2 + 2 e and equation. 2 a 8x + 2 – absolute an 24 3x + 8 = 0 Quadratic functions and equations f 12x – 20x + 25 = 0 of the 2.7. 18, EXAM-STYLE Find 2 real the QUESTION values of p such that the equation + 4x + p = 0 px b 2 x + real + px the + 8 = values 0 x d of k such that + the Find 10x + k = 0 2x b – 2kx the + 5 values = 0 of x d m such that + 1 = 0 has two equal x – 6x 3mx + + k = 0 – 4kx – 3k equation = 0 has no real roots. m = 0 x b + 5mx + 25 = 0 2 – 8x EXAM-STYLE Find 3x 2 2 5 3px – the 2 c 0 2 3x a = 2 + 2 4 2 roots. x c + equation 2 a 5x 2 Find 3 different 2 x c two roots. 2 a has + 1 = 0 x d + 6x + m – 3 = 0 QUESTION the values 4qx + of q for which the quadratic equation 2 – qx 5 – q = 0 Investigation will – have no graphs real of roots. quadratic functions 2 Each For of these each functions is given in the form y = ax + bx + c. function, 2 i nd the ii graph value of b – 4ac For the function on your 2 a y = x c y = x 3x – 5 b y = 3x d y = 4x 2 y = x g y = – 2x + 7 do – x 6x the quadratics on a – 6x + see Chapter 17 Section 1.6. 4 + 3x + 5 + 9 5x + f y = 2x h y = x 2 examples between graph – 4x + 2 2 + these relationship and graphing 2 2 What with 2 + 2 e GDC, 2 – help GDC. of a the suggest value quadratic of to + you the 7x + about 3 the discriminant function? y . Graphs of quadratic functions 2 A function where we a will ≠ of 0, look the is at form called the a y = ax of = x 2 + bx quadratic graphs 2 y + c, or f function. quadratic (x) In = ax this + bx + c, section, functions. 2 The This simplest graph quadratic has a function minimum at is the y = x point . Its (0, graph 0), and is it shown. is symmetrical 0 about the x y-axis. Chapter If you look notice at some the graphs of other 2 y = quadratic functions, you should similarities. 2 x + 2x – 1 y = 2 3x – y 4x + 2 y = –2x + 2x + 3 y y 0 0 x x 0 Each of these Each graph graphs also has has a a cur ved minimum x shape or a known maximum as a parabola. point called a vertex 2 If the with coefficient the ver tex of as x is the positive, minimum the parabola point on the will open upwards, graph. 2 If the coefficient downwards, and of is x the negative, ver tex will the be a parabola will maximum open point. y If a you imagine parabola, and is right called in red you sides the on a will of axis this ver tical notice this of line r unning the ver tical graph line. symmetry . through is ver tex symmetrical This This the imaginar y axis of on of the ver tical symmetr y is left line shown graph. 0 We will now Consider the look at graphs different of these forms of quadratic quadratic x functions. functions in the form axis 2 y = ax y = x + bx + c: 2 2 + x – 3 y = – 0.5x 2 – 2x + 4 y = – 3x + 3 1 x = 1 y y y x x – = 2 2 (0, 4) (0, 1) 0 0 x x 0 x (0, –3) = x –2 2 ➔ For the quadratic graph functions crosses the in standard y-axis at (0, form y = ax c). b The equation of the axis of symmetr y is x = 2a Quadratic functions and equations + bx + c, of symmetr y 2 ➔ When the basic quadratic function y = x undergoes Y ou transformations, the resulting functions can be written might want to look as back at the section 2 y = a(x – + h) k about Look at the graphs of these quadratic functions in the = a (x y = (x – h) + 2 2) – of this in Chapter 1 book. k: 2 – graphs form 2 y transformations of 1 y = 2(x + 1) y 2 – 4 y = – (x y – 3) + 2 y (3, 2) 0 x 0 0 x x (2, –1) (–1, –4) 2 ➔ For quadratic has its functions in the form y = a(x – h) + k, the graph This ver tex at (h, form quadratic is Example of a k). function sometimes ‘turning-point 2 a Write b Sketch called the function the graph y of = x the form’. 2 – 6x + 4 function, in the form labeling the y = (x – ver tex h) and + k the y-intercept. Answers 2 a y = x – 6x + 4 By looking standard at the for m, y-intercept will equation you be know in the (0, 4). 2 y = (x – 6x + 9) + 4 – 9 Use ‘completing the square’ to rewrite 2 y = (x – 3) – 5 the equation. subtracting b By 9, adding the value 9, of then the right- y hand side of the equation has not changed. 0 x (3, –5) Note: of The equation symmetr y is x = of the axis 3. Chapter Example 2 a Write the function f (x) = 2x + 8x + 11 in the form labeling the ver tex 2 f b (x) = a(x Sketch and – the the h) + k. graph of the function, y-intercept. Answers 2 a f (x) f (x) f (x) = 2x + 8x + 11 The y-intercept of the graph 2 = 2(x + 4x + 4) + 11 – 8 is (0, 11). 2 = 2(x + 2) + 3 Be b careful when completing the y 2 square if Factor out the x the ter m has coefficient a coefficient! from the 12 (0, 11) first 10 8 By two ter ms. adding 2 × 4, then subtracting 8, 6 the value the equation of the right-hand side of The 4 (–2, 3) has not name ‘parabola’ changed. was 2 introduced Apollonius 0 –5 –4 –3 –2 axis The of Exercise 1 For 1 2 equation symmetr y of is x the = 190 −2. on function, write the equation of symmetr y and give the y-intercept BCE) conic in BCE– his wor k sections. can nd graph of each the ver tex and the of y-intercept the 262 the Y ou of c. H each axis Perga x –1 (Greek, Note: of by function. See points Chapter 17 using your Section GDC. 1.8. 2 a f (x) = x + 8x + 5 2 b f (x) = x c f (x) = 5x – 6x – 3 2 + 10x + 6 2 d 2 f (x) = For each and give – 3x + 10x function, + 9 write the coordinates of the ver tex It the coordinates of the y-intercept of the may be helpful substitute 2 a y = (x – – 2 b y = (x + 5) + = 4(x – 1) + 6 d y = 3(x + 2) – the the each graph function of the in the function, form f (x) labeling = the a (x f (x) = f (x) = h) + and k. Then x + 10x – 6 b f (x) = 3x x – 5x + + 8x 2 2 – 6x + 7 Quadratic functions and equations d f (x) = –2x sketch the y-intercept. 2 2 c – ver tex 2 a or the function in 7 2 Write 0, 2 standard 3 = 1 write y x 2 7) 2 c to graph. – 3 form to y-intercept. nd W e will For now consider obvious Look at y = a(x y = (x the – + reasons, graphs p)(x 3)(x – – quadratic we of functions sometimes these call quadratic in the this form y the = a(x – ‘factorized functions in the p)(x – q). form’. form q): 1) y = –3(x y + 1)(x – 4) y = (x + 2)(x – 5) y y –12 20 8 16 4 12 0 x 4 8 0 x –8 4 –12 0 x –16 –4 –8 ➔ For quadratic graph For crosses functions the quadratic in x-axis at functions the ( p, in the form 0) y and form = a(x at y (q, = of symmetr y will have the equation x p)(x – q), the – q), the 0). a(x p – – p)(x axis + q = 2 Note: tell The us For the + roots example, crosses (x x-intercepts the 3)(x – of in the x-axis 1) Example = the at 0 of the graph quadratic first graph (–3, 0) has x = a quadratic equation above, and roots of at –3 (1, the 0). and x in the form f function y The = function y = (x) (x = + = f (x) 0. 3)(x – 1) equation 1. 2 Write Then the function sketch the f (x) graph = of x + the 3x – 10 function, in the form labeling the f (x) x- = (x and – p)(x –q). y-intercepts. Answer 2 f (x) = x + 3x f (x) = (x + 5)(x – 10 – The 2) graph Factorize will the cross the right-hand y-axis side of at (0, −10). the equation. y 0 x (0, –10) p Note: The equation of the axis of symmetr y use x + q = 2 ( is x 5) + = 2 3 = 2 2 Chapter Example 2 Write the sketch function the graph y of = 2x the – x – 3 in function, the form labeling y the = x- a(x and – p)(x – q). Then y-intercepts. Answer 2 y = 2x – x – 3 y = (2x – 3)(x y = 2(x – 1.5)(x The y-intercept of the graph will be (0, −3). + 1) Factorize the right-hand side of the equation. + 1) Factor first y 0 out the coefficient of x in the factor. x (0, –3) Note: The equation of the axis 1 of symmetr y x is = 4 Exercise 1 Write I the coordinates of the x- and y-intercepts of the graph It of each may be helpful substitute a f (x) = (x c f (x) = – + 3)(x 3(x + – 7) 2)(x + 1) b f (x) = 2(x – 4)(x d f (x) = 5(x + – 6)(x – 5) write 2) Write the each graph function of the in the function, form y = labeling a(x – the x- 2 a y = x and y = – q). Then x 7x – 8 y b = x – –2x + form sketch 15 2 + 3x + 5 y d = 5x + 6x – 8 2 3 Write form each y of the a y = function a(x – p)(x function, – in the q). form Then labeling the y = a(x make ver tex a – neat and x y = k and sketch of and in the the graph y-intercepts. 2 + 6x – 16 y b = –x 2 c + the x- 2 = h) –0.5x Exam-Style – 4x + – 18x 21 2 + 3.5x – 3 y d = 4x + 8 y Question 2 4 Let f (x) = 2x A – 12x. Par t of the graph of f is shown. 0 a The graph crosses x-coordinate i Write c The x-axis ii down ver tex at A and B. Find B the of A b the the of B equation the graph of is Quadratic functions and equations at the C. axis Find of symmetr y . the coordinates of C 0, to y-intercept. y-intercepts. 8x = C or function 2 – 2 c p)(x the standard the 2 to function. x in nd Exam-Style Question 2 Let 5 f (x) = Find a x (f + g) 3, and let g (x) = x – 2. (x). ° Write b down the coordinates of the vertex of the graph of (f g). ° The (f graph g) by 5 of the units function in the h is formed positive by translating x-direction, and by 2 the graph units in of the ° negative y-direction. Write c the equation of the function h (x) in the form 2 h (x) = Finding can ➔ of a lot the When ● + c down the equation from tell equation bx write the function Y ou + ax Hence, d a of a of the graph of h quadratic graph about the function the y-intercept in equation graph of a different is function by looking at the forms. written in standard form 2 f (x) = ax + bx + c, you know the y-intercept of the graph is b (0, c), and the equation of the axis of symmetr y x is = 2a 2 When ● the known ● When the f = a(x at (q, (x) and Now you function If If you will from know you are given Example write the the Write equation – in p)(x – is q), the form form, written the the in graph f (x) = a(x ver tex will factorized will – cross h) be + (h, k, also k). form the x-axis at (p, 0) 0). look the is tur ning-point at how you information the x-intercepts, tur ning-point Using as equation the ver tex, can find given begin you in with can the its the star t equation of a quadratic graph. equation with the in factorized equation form. in form. information equation your final of provided the answer in the quadratic in standard graph, y function. form 2 y = ax + bx + c 0 (–2, 0) (4, 0) x (0, –16) { Continued on next page Chapter Answer y = a(x + 2)(x – 4) Since with the the x-intercepts equation in are given, factorized star t for m. You know that y = −16 when x = 0. – 16 = a(0 – 8a = –16 + a = 2 y = 2(x 2)(0 – 4) Substitute your You + 2)(x – these equation can values to check solve this into for a. answer by 4) graphing the equation on your GDC, 2 y = 2x – 4x – 16 and to comparing those in the the x- given and y-intercepts graph. GDC help on screenshots Plus and GDCs Example CD: for Casio are on Alternative the TI-84 FX-9860GII the CD. y Write the equation in graph. of the quadratic function shown (6, 3) the 2 Write your final answer in standard form y = ax + bx + c. 0 x (0, –15) Answer 2 y = a(x – 6) + 3 Since the ver tex tur ning-point 2 – 15 = a(0 – 36a + 3 = – 36a = – 18 6) + 3 You know values 15 You on into can your is given, star t with the equation in for m. that y your check GDC, = −15 when equation this and to answer by checking x = solve 0. Substitute for graphing the these a. ver tex the equation and the y-intercept. 1 a = – 2 1 2 y = – (x – 6) + 3 2 GDC help on screenshots Plus and CD: for Casio Alternative the TI-84 FX-9860GII 1 2 y = – x + 6x – 15 2 Quadratic functions and equations GDCs are on the CD. Finally , or the three let’s axial look equations Example Write the at what intercepts in of three happens the if graph. variables to you This don’t next solve know the example using a ver tex also leads to GDC. equation of the quadratic function shown in the graph. y (–2, 9) (4, 3) x (2, –7) Answer For the point (–2, 9), In this case, you are given the coordinates of 2 9 = a(–2) 9 = 4a For the – + 2b point b(–2) + (2, + c three points on the graph of the function. c Substitute –7), the x- and y-coordinates of these three 2 –7 = a(2) + b(2) –7 = 4a 2b + points c into the standard-for m quadratic equation 2 For the + point + (4, y c 3), = ax + You now You can bx + have c. three equations with three variables. 2 3 = a(4) 3 = 16a GDC help solving on the on CD: b(4) 4b TI-84 Plus GDCs + Help simultaneous FX-9860GII the + + c use your GDC to solve for a, b and c. with equations and is + c Casio given on CD. To find see Chapter If Using the GDC, a = 1.5, b = −4, and c = −5. you will these 17 graph see points that Section this it on the 1.5. function passes graph, on through your all GDC, three you points, 2 y = 1.5x – 4x – 5 as described. Chapter Exercise Use the J information provided in the graphs to write the equation 2 of each function in standard form y y = ax + bx + c y y (–1, 8) (0, 5) (–2, 0) 0 (6, 0) x (0, 5) (0, –12) 0 x (2, 1) 0 x y y y (1, 13) (5, 30) 0 (15, 30) x (–4, 8) (0, 4) (20, 0) (4, –5) x 0 y x y (2, 25) (1, 3) (–3, 0) (7, 0) 0 x 0 Quadratic functions and equations (0.5, 0) x . Applications At the by water beginning in Quadratic different When you use a a quadratics chapter, can and be you saw modeled their graphs that by can a the shape quadratic be used to formed function. model many situations. solving lear ned your problems throughout GDC farmer If this functions Example A of fountain of to this you quadratics, chapter. answer Y ou many you will can use also be the methods expected to questions. wishes the help using garden to is enclose x metres a rectangular wide, find garden the length with and 100 the metres area of of fencing. the garden in terms of x 2 b Find the width c Find the maximum of a garden area with the an garden area can of 525 m have. Answers a If of 50 – the far mer the has rectangle 100 m must of be fencing, 100. The the sum perimeter of the length x and width will therefore be 50 m. x length area = = 50 x(50 – − Area x Set b x(50 – x) = = width × length x) 525 the Write area as a equal to 525. quadratic equation in standard for m, and 2 50x – x = 525 + 525 solve for x. 2 x – 50x (x – 15)(x – = 35) 0 = 0 You the x = 15 m or 35 m could also square, or solve by this using equation the by quadratic using your If the width is 15, the length is 35. If the width is 35, the length is 15. completing for mula, or by GDC. y c The (25, 625) easiest way to find the maximum area is to 600 graph the and is x function the width. y = x(50 You can – x), do where this on y is your the area GDC. 400 See 200 Chapter The ver tex graph, and 17 (25, Section 625) tells you is 1.6. the the highest point maximum area on the occurs when x –20 the width of the garden is 25 metres. 2 The maximum area is 625 m Chapter Example The height of a ball t seconds after it is thrown is modeled by the 2 function a Find b For h = the 24t – 4.9t + maximum what length of 1, where height time h is the reached will the by ball height the be of the ball in metres. ball. higher than 20 metres? Answers a Graph y the function (2.45, 30.4) 2 30 y 25 height = 24x – of 4.9x the + ball 1, where and x is y is the the time in seconds. 20 The ver tex is approximately 15 (2.45, 30.4). This tells you the 10 maximum height occurs when the ball 5 has 0 x 1 2 3 4 been You 5 can GDC. The maximum height the find See air the for 2.45 ver tex Chapter seconds. using your 17 is Section 30.4 in 1.8. metres. 2 20 b = 24t – 4.9t + 1 Let h + = 0 Write = 20. 2 4.9t – 24t 19 as a standard You See t ≈ 0.9930 seconds and 20 – 0.9930 = ball is metres and 2.912 solve Chapter The 3.905 seconds 3.905 can quadratic for m, once and this 17, at a using Section height twice, on equation solve once for in t. your GDC. 1.7. of on the way up, the What The ball will be higher way than other real-life 20 metres for be Example takes Luisa 3 hours to ride her bicycle up a hill and back down. −1 Her average average the top speed speed of the riding riding hill is up 40 down the hill the is the hill. If km, find Luisa’s 35 km distance h faster from average the uphill than her bottom and to downhill speeds. Answer distance Let x represent Luisa’s uphill Remember time = , and speed riding speed. when 40 you add = x 3 downhill times, uphill the total and is + 35 3 hours. { the 40 + x modeled by seconds. quadratic It of situations about might 2.91 kinds down. Quadratic functions and equations Continued on next page functions? You can multiply through by x, and 40 x 40 + = 3x then x by (x + 35), to get rid of the + 35 denominators. 2 40x + 1400 + 40x = 3x + 105x Write as a quadratic equation 2 3x + 25x – 1400 = 0 in standard using your Section for m and GDC. See solve for x Chapter 17, 1.7. −1 x ≈ 17.8 km h −1 Luisa averages 17.8 km h riding −1 uphill, and 52.8 km h riding downhill. Exercise 1 The K height of a ball t seconds after it is thrown is modeled by the 2 function h = 15t – + 4.9t 3, where h is the height of the ball in metres. a Find b For 12 the maximum what length of height time reached will the by ball the be ball. higher than metres? 2 2 The area, A cm , of a rectangular picture is given by the 2 formula A = centimetres. 32x – Find x , the where x is the dimensions width of the of the picture picture if the in area 2 is 3 252 A cm piece are If a of the side 40 into side that cm two length length Show b wire formed of the the long is cut into two pieces. The two pieces squares. of one other of the squares is x cm, what is the square? combined area of the two squares is given by the squares? 2 A A a is 20x the same The of the length width. as 100. por trait measures frame the area combined of of 50 uniform the area cm of by width. por trait, 70 If what two cm. the is It is area the surrounded of the frame approximate frame? of Find + minimum rectangular the width 5 – rectangular by is 2x What c 4 = a the rectangle is dimensions five of less the than three rectangle if times its its area is 2 782 6 The is m sum 251. of Find the the squares of three consecutive positive odd integers integers. Chapter 7 A ‘golden rectangle’ has the proper ty that if it is divided into The a square and a smaller rectangle, the smaller rectangle will length-to-width be ratio similar in propor tion rectangle ABCD rectangle PBCQ, A to below , as the PQ original forms a rectangle. square In the APQD golden and a rectangle a as shown. P of the ratio. B to golden is Y ou this BC may investigate situations AB known golden in want other which interesting ratio = AD D Q Given 8 A a house. the One builder has area the of Jaswinder away . He = 1, find wants side other appears. C AD homebuilder and 9 that PB of three takes a travels the sides enough largest to build deck will wood deck trip 360 AB for he to km a rectangular will 15 by a wall of on with the railing. railing, the If back of house, the what is the build? his bus, a wooden metres could visit share have deck sister, and who 140 lives km by 500 km train. −1 The train entire the 10 bus and Working than the averages jour ney the in 2 John If faster h hours, if takes they hours house Review km 8 find than the the bus. average If the speeds of train. does. house clean the alone, Jane 10 takes work 24 he two is more hours together, minutes. working John How long to clean and the Jane does it house can take clean John to alone? exercise ✗ Solve each equation. 2 a (x + 2) = 16 2 b x c 3x –16x d x + 64 = 0 2 + 4x – 7 = 0 + 12 = 0 – 12 = 0 = 0 2 – 7x 2 e x + 2x 2 f 3x – 7x + 3 y EXAM-STYLE QUESTION 2 Let f (x) = x + down 3x 4. Par t of a Write b Find c Write down the equation d Write down the x-coordinate the the – y-intercept x-intercepts of Quadratic functions and equations the of the of the graph graph of of f is shown. f 0 graph. the of axis the of symmetr y . ver tex of the graph. x EXAM-STYLE QUESTIONS y 25 3 Let f (x) = a(x – p)(x – q). Par t of the graph of f is shown. 20 The graph a Write b Find passes down through the value the of points p and of (–5, 0), (1, 0) and (0, 10). q 10 the value of a 5 0 –2 –3 x –1 2 4 Let f (x) = Write a a(x + down b Given c Hence that 3) – the f 6 Quadratic coordinates (1) = 2, find of the the ver tex value of of the graph of are f closely other the value of f a related functions ‘conic find functions to called sections’ (see (3). page 60). How are 2 5 The equation Find the Let (x) x + possible 2kx + 3 values = of 0 has two equal real roots. k these functions in real the used world? 2 6 f = Write a 2x + the 12x + function 5. f, giving your answer in the form 2 f (x) The b = a(x graph units in – of the y-direction. + h) g is k. formed positive Find by translating x-direction the and coordinates of 8 the units the graph in the ver tex of of f by 4 positive the graph of g y 7 Write the function Give equation shown your in answer of the the in quadratic graph. the form 2 y = + ax bx + (–4, 0) c. (6, 0) 0 x (2, –12) Review 1 Solve exercise each equation, giving your 2 3x a – 5x – 7 = 0 2x b x = The 2x – 1 to 3 significant figures. 8x = 3 1 + d + 3 x EXAM-STYLE 2 + 1 c x answers 2 = 5 x + 2 QUESTION height, h metres above the water, of a stone thrown off a 2 bridge t is the is modeled time in by the seconds function after a What is the initial b What is the maximum c For d How what length long does of it the height take stone from height time is for h(t) is 15t which height stone + 20 – , 4.9t where thrown. the reached the the = by of to stone the the hit is stone the thrown? stone? greater water than below the 20 m? bridge? Chapter 3 The length The area of a rectangle is 5 the rectangle is 1428 cm more than 3 times its width. 2 width of of the EXAM-STYLE cm . Find the length and rectangle. QUESTION 2 The 4 of f function is The f is given by f (x) = ax + bx + c. Par t of the y graph shown. graph of f passes through the points P(−10, 12), Q(−5, −3) R and R(5, Find the 27). values of a, b and c P Thomas 5 drives his car 120 km to work. If he could increase 0 x −1 his average minutes speed faster. CHAPTER Solving ● ● If xy 0, then x = This proper ty can To a)(x solve equation. of − an coefficient side his quadratic is − is km b) , he would average make driving it to work Q 30 speed? or equations y = 0. sometimes be = x, This the 0 0, by square step called expanded then equation of h SUMMARY proper ty (x 20 What This If ● = by x − a the zero product property to: = 0 or completing it, and creates a add x the the perfect − b = 0. square, result square to take both half the sides trinomial on of the the left equation. 2 ● In order to complete the square, thecoefficient of the x term 2 must be factor The 1. out If the the x term has coefficient, quadratic or a coefficient divide other through by than the 1, you can coefficient. formula 2 ● For any equation in the form ax + bx + c = 0, This formula is given 2 −b x ± b − 4 ac in = the IB Formula 2a booklet Roots of quadratic need equations to so you do memorize not it! 2 ● For a quadratic equation ax + bx + c = 0, 2 ■ if b Y ou – 4ac > 0, the equation will have two different can think of an real equation with two roots equal 2 ■ if b ■ if b – 4ac = 0, the equation will have two – 4ac < 0, the equation will have no equal real roots as having roots only one solution. 2 real roots. Continued Quadratic functions and equations on next page Graphs of quadratic equations 2 ● For the quadratic graph functions will cross the in standard y-axis at (0, form y = ax + bx + c = 0, c). b ● The ● When equation of the axis of symmetr y x is = 2a 2 the basic quadratic function y = x undergoes transformations, 2 the resulting functions can be written as y = a(x – h) + k 2 ● For the ● quadratic graph For the quadratic graph functions will have in the the ver tex functions crosses For quadratic its in the x-axis functions in form at at the (h, form ( p, y = a(x – h) + = a(x – p)(x 0) form y and y = at a(x (q, – – of symmetr y will have the p)(x equation x q), 0). – p the axis k, k). q), + q = 2 2 ● When the known ● as When the f = a(x at (q, (x) and equation is in tur ning-point equation – p)(x – is q), the form form, written the the in graph f (x) = a(x ver tex will factorized will cross – h) be + (h, k, also k). form the x-axis at (p, 0) 0). Chapter Theory of knowledge Conic sections: shapes The graph a parabolas air, or are sections. the cones) quadratic in the one of of conic a the real the circle, of The the function – is the streaming in world the path from shape of a a of a parabola. baseball flying We also through fountain. four as sections plane. real world water known intersection and are the shape shapes These by sections the just mathematical two of see Parabolas formed in mathematical conic are a cone other ellipse (or conic and the hyperbola. Circle { A parabola when a is the plane parallel to shape that intersects one of its a Ellipse results slanted edges. describe ancient sections, (c.262 – and 190 Hypatia died Greeks 415 Apollonius BCE) (bor n CE) studied first a 350 each equations of these and of the Parabola: y = Circle: (x ax² + bx and 370, h)² + (y – when few Alexandria, women Egypt, received – h)² work on They were Persian Omar Theory of She conic developed at a fur ther studied (x an – (y Khayyám knowledge: by the poet (c.1048–1131). Conic sections: = – k)² = 1 b² h)² mathematical shapes in the real world (y – k)² – a² Apollonius’ and k)² time sections. mathematician – + Hyperbola: education. to c Platonist a² in + and Ellipse: School used them. mathematician head be Perga (x astronomer can shapes. conic named between was of Hyperbola cone Mathematical The Parabola = b² 1 r² the ese see ever y Why is Did a circle you This Apollonius How shown had when do that the orbits of planets are shapes? wasn’t orbits ‘perfect’? know elliptical day. he you until the early hypothesized was think studying this 17th that and century . planets naming knowledge had such conic developed sections. over time? Nowadays, suspension bodies Who in we space, knew Look see help that Why us do think shapes How using can our the slicing – be describe and and a what people of shape cone and the tr y and spacecraft of satellite could would and in other dishes. result give parabolas in us such useful shapes that universe? other modeled and hyperbolas paths equations, you might you the understand around that ellipses, bridges, mathematical can see by to patterns mathematics gures and shapes mathematical use in mathematics the help us world do you equations? to around understand us? our world universe? Chapter Probability CHAPTER OBJECTIVES: Concepts 5.5a of trial, outcome, equally likely outcomes, sample space ( U) and n( A) event. The probability of an event A P(A) is = . The complementar y events n(U ) A and A′ (not A). The use of Venn diagrams, tree diagrams and tables of outcomes. Combined 5.6 events, the formula for P(A ∪ B). Mutually exclusive events: P(A ∩ B) = 0. P( A B) Conditional probability; the denition P(A | B) . Independent events; the P(B) denition Before Y ou 1 you should Add, + 3 = 5 P(A) how multiply 10 3 = = P(A | B′). Probabilities to: and divide Skills and without replacement. fractions 1 check Work these a = 15 out 1 b − a calculator. 5 1 c + 5 7 15 without 2 3 13 + 15 with start know subtract, 2 P(A|B) 7 2 × 5 3 3 2 1 2 9 – = 7 – = ⎛ 1 9 9 9 d 9 1 − 5 ⎞ ⎝ 3 3 20 e × ⎜ ⎟ 3 9 7 ⎠ 9 3 3 20 × = 4 7 4 7 = 4 × 7 Add, 20 4 5 3 ÷ 2 = 5 4 = 7 3 subtract 1 = 1 3 and 3 multiply 0 0.2 + + 0.9 × 3 0.4 Work these out. a 1 − 0.375 b 0.65 + 0.05 c 0.7 e 50% of × 0.6 30 d 0.25 × f 22% of g 12% 10% 0.64 0.62 0.75 2 × 0.2 of 34 × Calculate 52% 2 1 0.22 0.38 of of 0.8 0.34 Since then decimals 0.35 0.7 0.2 9 0.34 68 = 0.068 percentages 60 Probability = = 0.52 × 60 3 = 31.2 Check using your a answers calculator. to questions 1 and 2 ● What is the chance of it raining tomorrow? [ According US ● What is the likelihood ● What is the probability that I will pass my test? winning the football National of us match after noon? Am I to get to school on time if I catch the bus rather struck a than the Weather the probabilit y cer tain the this Ser vice, ● to government ’s by given of being lightning year in is train? 1 750 000 We consider ‘chance’, questions ‘likelihood’, like these all ‘probability’ the and time. We ‘cer tain’ use in the words ever yday speech. The probabilit y being struck lightning These words also describe mathematical probability . This from of mathematics spor ting averages helps to the us to understand weather repor t risk, and and the ever ything chance of This str uck chapter by lifetime 6250 probabilities lightning. looks at the language of probability , how to have been from data estimated on (give it a numerical value) and the basic tools you solve problems involving probability . of and need number to size quantify population probability is 1 These being an impor tant 80-year branch in of by struck the of by past people lightning 30 in years. Chapter Investigation During de the Which or is . Antoine rolling dice mathematicians Gombaud Blaise puzzled over Pascal, this Pierre simple problem: a likely, ‘double option do rolling six’ you on a ‘six’ 24 think is on four throws throws with two more likely? of one dice, dice? Why? Definitions An event An experiment A Some is random which ● and more rolling Which ➔ mid-1600s, Fermat gambling – an event a ● tossing ● picking may of dice a is the is an by one experiment. which where we there obtain is an outcome. uncer tainty over occur. random three coin from process experiment examples rolling outcome experiments are: The times on once of two cards from a pack of 52 playing rst recording 5-minute We can Chance 0 and represents probabi li ty number of cars that pass the and Book school gate in written by Games, Jerome a Cardan (1501–75). Cardan was period. express between 1 the written cards was ● book probability , The the 1. an chance On event that the this that event of an scale, is occurring represents cer tain will impossible 0 event to an happen. using a number impossible This is event called Italian and gambler . chance cer tain physician, His and book contained techniques on cheat how how 1 0 astrologer , philosopher , mathematician the happen. even an to to catch and others at 1 cheating. 2 We write P (A) to represent the probability of an event A occurring. A probability greater Hence There 0 ≤ are P (A) three ≤ than cannot be 1. 1. ways of finding the value of the probability of an Y ou can write event: probability decimal, ● theoretical as a fraction or probability percentage. ● experimental ● subjective probability probability . On a dice Theoretical fair the fair occur. dice The has list six of numbered equally sides, likely all of possible which are outcomes equally is 1, 2, 3, likely 4, 5, to 6. outcome same. dice, are On Probability a some more others. of probability each A (unbiased) probability is the biased outcomes likely than W e call n(U) Let = a 6 list event one 6. The of possible shows A be n(A) = that defined 1 as shows probability of outcomes there are six ‘the that getting number there a the sample space, members 6 is 6’. one when of In 6 you the this in sample the roll U. dice notation space. space sample the The sample there is space. is one out of 1 six, or . In probability notation, 6 n( A) P( A ) 1 = = n (U ) 6 n( A) ➔ The theoretical probability of an event A is P( A ) n (U ) where and ➔ If the the n(A) n(U) is is the the number total probability event to of occur an n of ways number × of event P that event possible is P, in n A can occur outcomes. trials you would expect times. A Example 20-sided polyhedron is called an icosahedron fair to 20-sided 20 is dice rolled. with The faces event A numbered is defined 8 1 as 2 A 20 Processes ‘the number obtained is a multiple of 4’. that are too 1 3 6 1 complicated to allow 41 P (A). The dice is rolled 100 exact 4 Determine 9 a How many times would you expect a 9 1 of solved using probability 1 multiple may times. be b analysis 4? that methods employ large the numbers’. ‘law of These Answers methods, a n(A) = 5 and n(U ) = Find 20 in n( A) P( A ) = 5 = n (U ) developed n(A) 1 There 4 these are 20 possible outcomes. 5 of the 40s, 1930s are and known = 20 16 are and multiples of 4 (4, 8, 12, as 20). Monte methods Carlo after the 1 × b 100 = Probability 25 × number of trials famous casino. They 4 are used variety Experimental Sometimes experiment (empirical) outcomes to are estimate not probability equally likely but you from can use is example, being components. conclude not be to find produced If that the the all case. by of If probability factor y first the the wide estimating of a the game the hand in an card ‘Bridge’ probabilities. the a a situations, strength to For in of is that faulty component we components second a we par ticular would test are is faulty faulty . component is not component test Y ou could However, this then statistics chain some we faulty that modeling may we to of the a nuclear reaction. may wish explore the applications of Monte method the could Carlo 1 conclude that the probability of a component being faulty since is 2 half of all components so far are fur ther . faulty . Chapter Continuing this process a number of times and calculating the ratio The the number of faulty US National components Weather the number of components used gives the relative frequency of the component being nd faulty . of As the number of Ser vice tes s ted components tested increases, the relative this the closer and closer to the probability that a component being is struck No. Y ou can The is use larger to the Example relative the frequency number of as trials, an the estimate closer the of of of people people relative frequency cars passing the school gate one morning are given in the table: Frequency Red 45 Black 16 Y ellow 2 Green 14 Blue 17 Gray 23 Other 21 T otal These 138 numbers estimates, Estimate the probability that the next car to pass the school are because using the red. relative The b are gates we be population probability . Color will in struck probability . The colors of a by using faulty . No. ➔ to frequency lightning , gets method probability next mor ning 350 cars pass the school an Estimate the number of red cars that frequency as gates. estimate of the mor ning. probability. Answers 45 The a relative frequency of red cars is This probability is 138 given as a fraction. In 45 So the probability of a red car is IB exams you need to answers or 138 give When b 350 cars pass the school decimals 45 the number of red cars will be approximately × 350 = Y ou can’t these cases subjective For win? last few performed played in, in but Probability look games the experiment the are due What at is past each par ticular eventually the play has weather will an and soccer the and conditions need to make event times. based Arsenal Liver pool two how the a of In on belief. against that between played number of probability matches you large information to team a probability experience, Liver pool could an estimate Premiership. Y ou the can judgment, example English as you repeat 3 sf probabilities. probability always to 114. 138 Subjective exact gate, as teams match ‘guess’. the will teams the in will well have be for Exercise 1 An A octahedral (eight-sided) dice is thrown. The faces are numbered In 1 2 to 8. What the a an b a multiple of 3 c a multiple of 4 d not e less A even is a that the number thrown is: multiple car probability all number than used probability ‘fair’, told of 30 of unless dealer the has cars 150 are used cars defective. on One his of lot. the The 150 dealer cars is What table random’ is the probability that it is below shows the relative the students Age (in any car years) frequencies of the chance 13 0.15 14 0.31 15 0.21 16 0.19 17 0.14 A an of being defective the cars is school. as likely as one that is to of be the not chosen cars defective. 1 student is randomly selected the student is 15 years old, ii the student is 16 years of are 1200 Calculate students the The sides of The table shows Number on a What six-sided the b Do the you this school. the age or Find the older. school. 15-year-old spinner for are 100 students. numbered 2 3 4 5 6 27 18 17 15 16 7 frequency spinner is from 1 to 6. spins. 1 relative think this of results spinner is at number Frequency a from that i There 4 high One of ages frequency probability b a has defective? Relative Total a at means at 30 of are knows selected selected. The you are otherwise. equal 3 questions, coins 4? that random. and 4 ‘At that dice of fair? getting Give a a 1? reason for your answer. c The spinner times 5 the Each letter card. The at the will word cards are 3000 be a times. Estimate the number of 4. CONSECUTIVE placed face is written downwards. A on card a is separate drawn random. What is a spun result of 11 is the the letter probability C b of the picking letter P a card c with a vowel? Chapter The 6 spinner getting green blue is twice that red Frequency 0.4 A bag is contains . an of Find even Venn biased. in The the getting probabilities table. The of getting probability of red and getting yellow . yellow blue green 0.3 probability random. a is shown Color Find the 7 shown are 40 the of getting discs green. numbered probability number, that 1 the has b to 40. A disc number the digit on 1 in is selected the at disc it. John diagrams Venn England There are 100 students in a year was in of them do Hull, father and were priests and John archer y . was This in His group. grandfather 38 born 1834. information can be shown on a Venn diagram also their to encouraged footsteps. Gonville and In to follow 1853 Caius he in went College, U Cambridge, A Set A is The becoming students represents For do 100 a archer y. Therefore n(A) n(U) the next = way is chosen at random. The probability Venn to student does 38 P( A ) archer y is written years and in 1857 college. he went returned 1862 into to teach to logic theor y. developed look at sets. a graphical This graph that became the in probability John student the 100. and A ve priesthood Cambridge 38. of students. the = graduated fellow the 38 who and rectangle known as a Venn diagram. P (A). 19 n( A) 100 Remember P( A) 50 = n(U ) Complementary The area students outside that do set not event A (but do A′ still in archer y . the This sample is A′, space the U) represents complement of the set A U A 38 62 n(A′ ) From The = n(U) the – n(A) Venn probability diagram that n ( A ) P( A ) a we see student 62 that does n(A′ ) not = do 100 – 38 = 62 archer y , 31 Ever y n (U ) 100 does Note student archer y or that doesn’t 31 P (A′ ) + P(A) = Probability 19 1 50 either 50 50 do archer y. ➔ As an event, A, P( A ) P( A ) P( A ) the Of those, Y ou 38 100 can do 22 do The the of 16 show 16 and does not happen. events 30 both this students archer y on a play and Venn badminton. badminton. diagram like this: do 30 do and 38 – = students badminton archer y. region students badminton. 16 16 U so 30 do just – do and 16 = archer y, 14 badminton 48 is B. This There represents students both written The as A 22 that archer y badminton. and it intersection those The or students shaded A do so just region is do badminton archer y, of students, students archer y. happens 1 P( A ) Intersection Of either 1 – are 16 and students region not ∩ 14 that – = 48 do archer y or badminton. B probability badminton do 100 − that is a student written P(A chosen ∩ at random does both archer y B). n(A in n(A ∩ B) = the B) is the number intersection of 16 the n( A B ) P( A B ) ∩ 16 n (U ) sets A and B 4 100 25 U A If a student is chosen at random then B the A probability that badminton but a student does do does not archer y is ∩ B′ do written P(A ∩ B ′). 22 students out of 48 100 22 P( A B ) do archer y but 11 not 100 badminton. 50 U A′ ∩ B ′ or represents the students who do not do badminton archer y . 48 A′ Chapter ∩ B′ Union of events The U of shaded A and those B, region The students archer y region or is is the region that represents do badminton written union either or both. The A ∪ B 48 Notice that ‘or’ mathematics The or probability badminton that is a student written chosen at random does either archer y the – we call ‘inclusive’ From the diagram, n(A ∪ B ) = 22 + 16 + 14 = it the or . is from the hence denition n( A B ) P( A B ) 52 A ∪ B ′ represents all of probability. 13 n (U ) do of 52 This and includes possibility both P(A ∪ B). in U 100 those 25 students that either do archer y or do not badminton. A ∪ B′ 48 n(A ∪ B ′) = 22 + 16 + 48 n ( A B ) P( A B ) In a Draw Use of and a hence 43 9 30 100 students, play Venn your and 50 group games 86 86 n (U ) Example = 17 play computer games, 10 play board neither. diagram diagram to to find a a student chosen at b a student plays both c a student plays board show the this information. probability random from computer games the games but not that: group and plays board computer board games, games, games. Answers Let B = C = plays plays Let x n(C ∩ = computer board n (C B ′) = ∩ games, You B ) 17 First − x ∩ B ) = 10 − don’t computer and use n(C ′ define your notation. games. x for know games this how many AND do board games; value. x U C B 17 – 10 – x 9 { Probability Continued on next page (17 36 − − x) x x + = = x + (10 − x) + 9 = The 30 four diagram 30 and 6 U so Solve regions make must for add the Venn universal up to set U 30. x. Substitute each of the x = section of 6 to the get the number in diagram. 9 Use 10 a the Venn P( B ) = = P ( A ) = 3 n (U 6 P(C ∩ B = 5 4 2 P(C ′ ∩ B ) = = 30 Exercise 1 In a and Draw a A child has 2 In the One of or 25 have many girl is to of that in taken have is a chosen 15 of study both random. she has taken both b she has taken gymnastics 7 the play One 32 have brown eyes. situation. that the child study French, 13 One from French have girl of them language. random both 13 and taken has the class. Malay? aerobics done What before neither before. activities? a Of 14 probability neither at group. gymnastics. at the them studies PE done brown this Find chosen he and hair, eyes. them students girls hair blonde represent brown 5 have random. students, and 25 at 10 blonde diagram hair Exam-Style 4 both selected these are 17 How children, probability There and 35 have Malay One of 3 4 Venn is class study is of blonde a 15 B group eyes, ) 1 ) = 30 c and n ( A) 30 b diagram 1 Find the probability that: activities, but not 18 play aerobics. Question students both. student How is in a many chosen a he plays golf b he plays the class, but at not piano play 16 play the piano and neither? random. the but golf, Find the probability that: piano, not golf. Chapter Exam-Style 5 The universal than or A B a b = A ii B 6 In the is both ii neither town subsets are the A set and multiples are factors of B of of positive are integers defined less as: 3} 30} of of chosen A at probability a as and B in the appropriate region U diagram. i a that that elements number the defined The elements Venn Find is 15. {integers Place a to U {integers the i A set equal = List on c Question multiple a 40% that of multiple of the random 3 the and of 3 from U. number a factor nor a population is of factor read 30, of 30. newspaper ‘A ’, For 30% read newspaper ‘B’, 10% you newspaper It is found both ‘A ’ Also, Find and 2% the random a c of ‘C’; the from read and reads reads both 3% people the only will three 5% probability reads b ‘C’. that this read that ‘A ’ read a question read and both all ‘B’ three person ‘B’; 4% and read Venn ‘C’. to circles to in diagram represent use the – one each newspaper . newspapers. chosen need at U town ‘A ’, only ‘B’, none of the three newspapers. C The addition rule Here is diagram the badminton Venn from page for the students who do archer y and 69. U The probability archer y a and student includes that the does the a student probability badminton does that each probabi li ty that a 48 student does badminton. n(A or n(A So, ➔ ∪ B) ∪ P(A For any Probability B) ∪ P(A = 38 = B) two ∪ + 30 n(A) = − + P(A) events B) = only archery wish to and include 16, n(B) + A P(A) both We − P(B) and + n(A − ∩ P(A ∩ B) B P(B) – this probability one of once so we B) P(A ∩ B) these probabilities. subtract Playing In the next familiar playing four example with suits – card Find is the a clubs, cards, you ordinar y In The Example A an cards. diamonds. black red cards pack need to be in pack of 52 10, there spades, clubs hear ts and and The are hear ts spades similar 2, or in the cards 4, 5, 6, 7, 8, 9, King. and picture cards 13 3, and Queen the to, are Ace, Queen Jack, playing are There suit: Jack, called and are diamonds cards. each King cards. your are Are countr y same as these? drawn at random probability that from the an card is ordinar y a hear t pack or a of 52 playing cards. king. Answer We require P(H ∪ K). U H Draw a Venn There are 13 There are 4 There is Using P( H diagram. K A ♥ K ♣ Q ♥ J ♥ 10 ♥ 9 ♥ 8 ♥ 7 ♥ 6 ♥ 5 ♥ 4 ♥ 3 ♥ 2 ♥ K ♥ K ♦ K ♠ hear ts in the pack. 13 P(H ) = 52 4 P(K ) kings in the pack. = 52 1 P(H ∩ K ) 1 card that is both a king and a hear t. = 52 So 13 P(H ∪ K ) 4 + = 52 1 – 52 4 16 = 52 = 52 ∪ K ) = P( H ) + P( K ) – P( H ∩ K ) 13 Chapter Example 9 If A and B are two events such that P(A) 3 = and P(B) = 20 P(A ∪ B) P(A a = ∪ 2P(A ∩ B ) B) find P(A b and 10 ∪ B )′ P(A c ∩ B ′ ). Answers Let a P(A ∩ B ) 9 = x Use 3 P (A ∪ B ) = P (A ) + P (B ) – P (A ∩ B ) 2x = + – 20 x 10 15 3x = 20 3 x = ÷ 3 4 1 x = = P(A ∩ B) 4 1 P(A ∪ B) = Since P (A ∪ Since P(A′) B ) = 2P(A ∩ B). 2 1 If b P(A ∪ B ) = then 2 1 1 P(A ∪ B )′ = 1 – = = 1 – P(A). 2 2 1 If c P(A ∩ B ) Use = result from par t a 4 P(A ∩ B ′ ) = P(A) – P(A 1 9 – = 20 ∩ This B ) is the diagram 1 region that is A on the Venn without its = intersection 5 4 with B. U P(B) P(A) 1 P(A ∩ B) = 4 Exercise 1 Two two The C dice are numbers shown following 500 on times. the frequencies dice are For is each throw , written the sum of the down. obtained: Sum 2 3 4 5 6 7 8 9 10 11 12 Frequencies 6 8 21 34 65 80 63 77 68 36 42 Using these thrown frequencies, calculate a the sum being exactly b the sum being an c the sum being exactly Probability the divisible even probability by 5, by 5 of number, divisible or being an even number. 2 A ten-sided probability 3 dice, numbered 1 to 10, is rolled. a the number scored is a b the number scored is either a prime c the number scored is either a multiple In a 22 group are of 80 females picked Calculate the that: from tourists with this prime 40 have cameras. group at number, number of cameras, Find random the is 4 50 or or a are a multiple multiple female probability either a that camera a of of 4, 3. and tourist owner or female. 4 A letter Find 5 is the chosen at probability random that it from a in the word MA THEMA TICS b in the word TRIGONOMETRY c in the word MA THEMA TICS and d in the word MA THEMA TICS or A a student work fiction What the is librar y . 0.40, non-fiction is fiction, b to fiction and What a goes of the the is 26-letter English alphabet. The work in in the the word word probability of TRIGONOMETRY TRIGONOMETRY that non-fiction is she checks 0.30, and out both 0.20. probability non-fiction, is a the is or that the student checks the student does out a work of both? probability that not check out a book? Exam-Style Questions 1 6 In a cer tain road of the houses have no newspapers delivered. 3 1 If 3 have a national paper delivered and 4 delivered, has have a local paper 5 what is the probability that a house chosen at random both? 1 7 If X and Y are two events such that P(X) = 1 and P(Y) 4 = and 8 1 P(X ∩ Y) = , find 8 8 a P(X ∪ Y) b P(X ∪ Y)′ = 0.2 If a P(A) P(A ∪ b P(A c P(A′ and P(B) = 0.5 and P(A ∩ B) = 0.1, find B) ∪ ∪ B)′ B). Chapter U Mutually exclusive In sur vey a student it is events found that A 32 students play C chess. 38 Chess time and so a archer y student clubs are cannot do on the both same day archer y at and the 32 same chess. 30 The events These same so are Now ∩ ∪ Generally follows Hence P(A = C ) if ∪ B) = = Example A box P(A) ∩ B) adapt P(A) ∪ two see hence + events In general, if P(A called can and P(A can are we two that we 0 C where Here C ) P(A and events time. n(A ➔ A that P(A and the ∩ – B cannot circles C ) = events. exclusive occur do not at the overlap, 0. 0. are mutually exclusive then it 0. the + outcomes P(C ) A = mutually addition r ule in these cases P(B). A and B are mutually exclusive, then P(A ∩ B) = 0 and B) = P(A) + P(B). contains board-pens of various colors. A teacher picks out a 1 pen at random. The probability of drawing out a red pen is the probability of drawing out a green pen , and 5 3 is 7 What is the probability red pen of drawing neither a red nor a green pen? Answer Let G R = P(R = green ∪ G ) pen = drawn, P(R) 1 + P(G ) define + R and 22 events. 35 The 3 = First your notation. drawn. G are mutually exclusive = 5 7 pen teacher or a either green draws pen, but out not a red both colors. 13 22 P(R ∪ G)′ = 1 – = Since Exercise 1 Here A: B: C: D: E: dice total there a A e B is two both Which some both the and and events show is at 7 are these B E or least dice dice of Probability = 1 – P(A). D are the P(A′) 35 35 a to throwing two dice: 4 more one show 6 the same number odd pairs b f relating of A C events and and C D are mutually c g A B and and exclusive? D C d A and E Exam-Style Question 1 1 Two 2 events N and M are such that P(N) = and P(M) = and 10 5 3 P(N ∪ M) = . 10 Are In 3 N a and and M group of 27 are a that In an students, a or 30 events? are freshmen (second-year student freshman Exam-Style 4 89 exclusive sophomores probability either mutually picked (first-year students). from this Find students) the group at random is school A winning sophomore. Question inter-school quiz, the probability of competition is the 1 1 , the probability of school B winning is and 4 3 1 the probability of school C winning is 5 Find the a A c none . or probability B wins of these Sample the the that competition, wins the space product A, b B or C wins, competition. diagrams and rule A Y ou can list all the possible outcomes of an experiment if there question you not too may tell are to list the possible many . outcomes. Example A fair as spinner shown is outcomes Hence is from find greater with spun the than the three this numbers times. 2 all and the 3 on it possible experiment. probability the 1, List scores that on the the score first two on the last spin spins. Answer The 1 1 27 outcomes 1 1 2 are: When 1 1 3 1 need not 1 1 2 1 2 2 1 3 2 1 1 3 1 2 3 1 3 3 2 1 1 2 2 1 2 3 1 2 1 2 2 2 2 2 3 2 2 1 3 2 2 3 3 1 1 3 2 1 3 1 2 3 2 2 3 3 2 3 1 3 3 2 3 3 3 3 Of these, score the on the the scores five last on 2 3 in miss all the outcomes, systematic any so that you you do out. 3 have greater first be 1 red spin the 3 3 listing to two the than spins. 5 Hence the probability is 27 Chapter Sample A sample space space outcomes of Example Draw Find a an sample the diagram is Sample another way of showing all the space diagrams possible event. are also called probability space diagrams. space probability obtaining a diagrams a diagram to represent the scores when two dice are thrown. of: score of 6 throwing b a double scoring c less than 6. Answers DICE 1 2 1 3 4 5 6 2 ECID 1 (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) (1, 1) 2 (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) score 3 (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) 4 (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) 5 (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) 6 (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) There are 36 possible outcomes illustrated on gives of a score of 2, (4, 6) gives a 10. this diagram. The 5 a P(6) five possible ways of getting highlighted 36 in DICE 2 ECID 6 P(double) = of 6 are 2 4 5 6 1 (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) 2 (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) 3 (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) 4 (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) 5 (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) 6 (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) 1 The six possible 6 highlighted in ways of getting a double are red. DICE 1 2 1 3 4 5 6 2 ECID 1 (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) 2 (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) 3 (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) 4 (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) 5 (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) 6 (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) { Probability 1 3 = 36 score yellow. 1 b a = Continued on next page 5 10 P(score c < 6) = The 10 ways of getting a score 18 36 highlighted in DICE 2 ECID In an Find less the the a sample coin space probability than 6 are 2 1 3 4 5 6 1 (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) 2 (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) 3 (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) 4 (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) 5 (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) 6 (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) experiment Draw than green. 1 Example less = 3 on the is tossed diagram that in a and for a dice this single is rolled. experiment. experiment you obtain a head and a number dice. Answer 1 2 3 4 5 (1, H) (2, H) (3, H) (4, H) (5, H) T (1, T) (2, T) (3, T) (4, T) (5, T) 2 P(head and number less than 3) Three H) (6, T) outcomes than 3 are that give a head and = One 6 coins possible are tossed outcome is one that at a all time the and coins the are results heads. are unbiased HHH. Another is that the first two coins are heads one is a tail. This is written that the Find 2 complete the a the b at c heads ‘Two probability number least Draw a two and the of heads tails tetrahedral the the 1 to number blue difference c the red the for just as heads up this random tails up. experiment. greater tossed tossed are the number of tails, consecutively , alter nately . diagram one They than blue for the random and the other rolled and the experiment red, result are each noted’. that: the red dice is greater than the number on the dice, the d dice, on b even are probability is are space 4. space is land that: heads sample numbered Find sample to HHT . as List is and likely last coin This one written the less = An is number Question unbiased noted. a highlighted. E Exam-Style 1 (6, 1 12 Exercise The 6 H dice between shows an the odd numbers number on the dice and the blue is one, dice shows an number, sum of the numbers on the dice is prime. Chapter Exam-Style Question Genetic 3 A box 1, 2, contains three cards bearing the ngerprinting numbers Genetic 3. A second box contains four cards in the numbers 2, 3, 4, 5. A card is chosen at 1984 each Draw the box. of sample space diagram for the random experiment. Find the probability a the cards b the larger have that: the same by number, University us has the two numbers drawn is the sum less d the e at of than the two numbers on the contained is inherited The DNA and body of one can cards bag. the numbers even number numbered One it is in the from DNA our extracted and one make-up and parents. from analyzed characteristics our ‘genetic When matching usual to cells to (seen ngerprint’. ‘ngerprints’ on the cards is at least is compare 0, 1, 2, is drawn at replaced in it is 3, bag. bands. of these comparisons have chosen. 4 random, the these 8, used and 5, are placed its number noted, Then a second as but evidence the eld to is convict under in due to its reliance on and probability. then Each genetic is scrutiny a be uids the – criminals cards, at 3, been Six Jeffreys Leicester . is Some 4 developed Alec 7, product least of unique which below) c a which produce of was Professor random the from ngerprinting with card Usually between 10 is and 20 bands are examined and chosen. compared. Draw the sample space diagram for the Experimental evidence random has suggested one band that the probability of experiment. Find the probability that: matching (although a the cards have b the larger the same the two coincidence numbers this gure is subject drawn is The probability of two prime, 1 matching the c sum less the d e 5 than least 8, at least one plays rolls metre. moves metre. the If If at exactly c more the 2 2 or numbers number with the metre. 6 he on 1 but If the cards will therefore is for rolled are not is it is called 1 he where away 4 He he he from than 2 a coin he the up If moves it and is left Go’. one 3 he one is. makes two steps. is star ted, his star ting metres is independent . influence is ‘Come moves independent and cards metre. he where that the from his star ting point? events tossed, This point, away is outcome as in Example because of be 16 chosen. dice twice. less is on rightone stays dice point a score moves metres events Probability numbers probability rule is If he the than does even one 5 the game same dice the coin is the b a is rolls is Product it a When a of dice. down Tilman What it two 7, at He page, the product Tilman the of is to 4 number, debate). of by 1 the rolling 9 on the outcome the dice and of previous tossing vice versa. bands ➔ Two events does not Here is the A the (1, Let H From (2, T) stand the for L stand dice (3, T) 4 H) (3, and (4, T) event ‘coin (5, T) lands occurs. 6 H) (5, one coin. 5 H) (4, a other of (6, T) H) (6, T) heads’. 2 for the event ‘dice score less than 3’. 1 4 = 3 12 L) There 1 2 ∩ a the occurrence 1 = P(H for that the = = P(L) chance if diagram: 12 Let independent 3 the 6 P(H) space H) (2, are the 2 H) (1, T B affect sample 1 H and = are outcomes coin we can also note ∩ L) P(H) = is than When two P(A B) ∩ This is the This is also Sample space possible One 1 bag red Find and a both c at A × 3. called and B are independent P(B) product rule the diagrams but for independent multiplication can you help you don’t events r ule. visualize always need the to number draw of one. contains the less 6 P(A) outcomes, Example is = 3 events = and score 1 × 2 ➔ heads dice P(L) × 1 1 = the that the P(H where 6 12 But two = 4 3 white red balls. probability the least balls one A 2 white ball is balls, selected another at bag random contains from each bag, that are ball and red, is b the balls are different colors, white. Answers 3 The a From the first bag P(R ) events ‘picking a red from the first bag’ (R = ) 1 1 5 and ‘picking a red from the second bag’ (R the second bag P(R ) = ) are 2 1 From independent events. In R 2 there are 3 red balls in 5. 1 5 In R there is events R 1 red ball in 5. 2 Therefore P(R 1 ∩ R ) 2 The and R 1 3 3 1 P( R 1 = × 5 ∩ R 2 ) = are independent, so 2 P(R 1 ) × P(R ). 2 = 5 25 { Continued on next Chapter page 3 From b the first bag P(R ) = If the balls are dif ferent colors, this means either the 1 5 first one is red and the second one white or the first one 4 From the second bag P(W ) = is white and the second one red. 2 5 Therefore P(R ∩ W 1 3 4 = ) 2 12 × = 5 5 25 2 From the first bag P(W ) = 1 5 1 From the second bag P(R ) = 2 5 Therefore P(W ∩ R 1 2 2 1 = × = 5 25 5 P(different P(R ∩ W 1 2 ) 25 = 1 = 1 P(W least – one exclusive events. ) 2 – P(R ∩ For white) probability R 1 1 R mutually 25 that both are – ‘at least calculate red probability ) one the of the balls probability that the first is that is white’ both white we are and could white, the the second red 2 and 22 3 = ∩ 1 are = 25 P (at + These = 14 + c colors) 2 12 ) 2 the probability that the first is red and the second = is 25 25 white. OR If at least one is white then it means that both cannot be red. This is involve a common the words complement Exercise 1 My wardrobe red, and choose shir t 2 A one contains white a shir t another. both card the at of solving least...’. is five and shir ts one without What is with black. I looking. the one reach I blue, into replace probability that one the choosing large this I shir t will and choose the chosen and a a at random second king school and card a from a deck of 52 cards. It is then is chosen. What is the probability questions of you It is three a sur vey found Probability are chosen students may need to ten? conducts cafeteria. students all and red times? of the food provided by remind yourself playing cards the that of the students like pasta. 5 that 2 then page Three the brown, 4 school that – wardrobe 8, A 1 event. For replaced 3 problems Calculate F one choose of method ‘… like at random. pasta? What is the probability 73. – about see Exam-Style 4 Adam is Questions playing in a cricket match and a game of hockey at the weekend. The and probability the Assume the 5 that Three events exclusive 6 ∪ C) = Determine a An a coin head will the team and = in C 0.2, the win such P (C ) cricket hockey matches will are win the are in that = 0.3, is is What is matches? and P (A 0.75, 0.85. independent. both A match match B ∪ are B) = mutually 0.4 and 0.34. b toss his P (A) Calculate I B team winning results A, and his of that a get 7 the probability P (B that probability P (B) air-to-air P (B whether and on and roll the a and C ). C are six-sided coin, missile B ∩ and has independent. dice. don’t get Find a 6 8 probability the on of probability the that I dice. hitting a target. If five 9 missiles not 8 with a cards 10 is from a the probability chosen What is standard the deck probability P (E ′ ) P (F ) = 0.6 and P (E explain why E and F are independent, c explain why E and F are not d find P(E bags the target is is the playing choosing 4 cards hear ts and B = are ∩ blue dice is = 0.24 mutually exclusive, is the 4 from red each that and the and first third probability blue marbles. One marble bag. the numbered: 8 1, marble marble 2, that 2, 5, the will be red, the red? 6, 6. It scores is add thrown up to three 6? Question 0.3. P (A contain probability What F ) F ′ ). chosen marble Exam-Style P(B) 52 P(E ), each six-sided times. a ∪ randomly second A of of ∩ b Three down = write A that Question that a What 12 are replacement. Given is 11 what row? Exam-Style 9 launched, destroyed? Four in are independent events such that P(A) = 0.9 and Find: B) b P (A ∩ B ′) c P (A ∪ B)′ Chapter Exam-Style 13 Independent and P(G′ Draw Let 15 I a ∩ events H) Venn P(G Find 14 Question ∩ two throw = and = possible to dice. values Find four dice show a b all four dice show the more such represent likely: of the all is are that P (G ∩ H ′ ) = 0.12 the events G and H x. a Which H 0.42. diagram H) four G x probability that 6, same rolling number. a ‘six’ on four throws of one dice, This or rolling a ‘double six’ on 24 throws with two you 16 A program produces (independently) three is to 9. For random digits from or 309 or 088 a Find the probability that none b Find the probability that at Investigation following American The is a – the famous television name comes game from least Monty probability show the of the one digit original a on closed opens After for the one of he has par ticipants last time the What being. two opened should After they you Monty remaining one whether remaining are: of the want have Hall, doors doors to stay always shown with their the the main other three prize two doors prizes the are doors door , the is reveals dud, rst door behind an the doors, unwanted Monty choice remains or Hall to then prize. asks switch the to the door . you do? We a Stick with doors. prizes. unwanted behind show of show. what a is game choice unwanted the randomly a the the door dud, the knows and on behind and chosen who and one are before Hall. given and car placed game 5. 5. you’re you’re there the a the Monty car) The a is Deal’. Behind of 64. di lemma host, (a digits is based Make and rules your rst will revisit Switch c It to the other remaining closed Probability not matter . Chances are at the door . this does this choice. problem b the on 936 three Hall puzzle ‘Let’ s show’ s or Suppose The in Investigation example 247 The question considered dice page 0 the dice? even. chapter . end of . Conditional Here is the Venn probabi li ty diagram showing students who do archer y and badminton. U 48 If we know affect the do write 30 par ticular the that students a how does this archer y? of student these does 16 also archer y do archer y . given that they that A| B ( ) 16 = is known dependent 8 = as 15 conditional the on = 30 n( B ) This do badminton, ) n( A B ) P also does badminton; that P ( A| B as student they do probability badminton Note a probability Altogether We that outcome since probability of the outcome of A is B. 16 P( A B ) It also follows that P ( A| B ) 100 = = 30 P( B ) 100 16 = 8 = 30 ➔ In general occurring for two given events that B A has and 15 B the occurred probability can be found of A using Recall that for independent events P( A B ) P ( A| B ) = P(A ∩ B) = P(A) × P(B). P( B ) By denition independent Rearranging the formula of ∩ B) = P ( A| B ) × A B, the occurring that occurred If A and B are independent A| B ) = P(A), P ( B|A ) = P(B), P ( A| B ′ ) = P(A) P ( B | A′ ) = will has equal probability occurring , not and B events, the ( A probability P(B). given ➔ events, gives and P(A for of since affected by A A is the P(B). occurrence of B. Chapter Example Of 10 the 53 drink How a One staff at neither many member school, nor staff of drinks a tea drink staff tea is but 36 drink tea, 18 drink coffee, and coffee. both chosen not tea at and coffee? random. b he c if he is a tea drinker he drinks d if he is a tea drinker he does Find the probability that: coffee, coffee not as drink well, coffee. Answers Draw a a Venn diagram to show the U infor mation 36 – 18 – x 10 n( T Let n (T ∩ C ) = ∩ C ) is the number who drink x both tea and cof fee. so 53 36 – 64 – x x x + x = + 18 – x + 10 = is the total number of staf f on the 53 Venn diagram. Solve for Since x 53 = x. 11 11 Therefore P(T ∩ C ) = = 11 and total = 53. 53 25 P(T b ∩ C ′) = 36 – 11 = 25 33 11 P(C ∩ T) P(C|T ) c = 53 = 36 P(T) 53 11 53 × = 53 11 = 56 36 25 P(C′ ∩ T) P(C ′|T ) d = 53 = P (C ′ ∩ T ) = P (T ∩ C ′) 36 P(T) 53 25 53 × = 53 Exercise There Four One are do 36 G Exam-Style 1 25 = 36 Questions 27 students neither person is in subject. chosen at a class. How he or she takes Theater b he or she takes at c he or she takes Theater, least take many random. a Probability 15 but one given and students Find not of Ar t the do 20 take both Theater. subjects? probability that Ar t, the two that he subjects, or she takes Ar t. 2 For events P(A) 48% a and ∩ of A B P(B) all is is 1 own roller blades at P(A′ ∩ B ′) = 0.35; a skateboard that What the random 4 P(B ′|A′). c blades. given chosen 2 that: Find P(A|B) b and known 0.6. teenagers roller number it = B) skateboard owns 4 A 0.25; P(A a 3 = 7 and is teenager from this 11 39% the of all teenagers probability owns list a of 16 that a own teenager skateboard? eight 22 numbers: 29 Find: 5 a P (it is even b P (it is less than 15 c P (it is less than 5 d P (it lies In my a town 6 The 0.1. is The the U P (V) 8 A V = A are and on first The that less and 20 | it 4) than than 5) 15) lies households between have computer household a student that that of draw table players in her both a has a takes student student exclusive P (U class tests those a and a 5 and desktop a laptop 25). computer. 61% computer. What laptop Design takes takes computer given Technology Design Spanish events. |V) an and who black The P (U) and IB white 0.34, and is 0.47. What draw , Paper passed probability the given is P (U c 52% is second Exam-Style 10 a b gave marble the is of greater that of all is it has and Spanish Technology given that the is 0.6. is What student is = 0.26; Find replacement. the multiple is desktop that V) contains white it 10 mutually 0.37. passed jar | a it computer? percentage 9 | all probability teacher class not Technology? P (U a a probability and is of have probability taking 7 95% probability desktop it between households the | of 1 the the and first test selecting the a of first also Paper the of chosen black a was the What second and selecting drawn of test. the are a 35% first marble selecting marble 2. passed marbles black probability the IB passed Two probability that V). an class marbles. of or without then a marble white test? on marble black? Question below a shows sample of the 50 number males of and left- Left-handed Right-handed Total 5 32 37 Female 2 11 13 Total 7 43 50 probability player that and the a male c right-handed, was selected player left-handed, given at right-handed table-tennis females. Male A table-tennis and random from the group. Find the is: b that right-handed, the player selected is female. Chapter J 11 and P(K) Y our 12 K = are independent 0.5, find neighbour Sam. What is P(J) has the events. two children. probability Investigation Given that P(J |K) = 0.3 and . – the that Y ou lear n Sam’s Monty that sibling Hall he is a has a son, This brother? as it is not as might obvious seem! problem revisited! T ake a typical contestant that there What is behind Let A Let the Hall the chosen an the Door unwanted game. 3 and prize Suppose Monty behind probability Hall Door that the the reveals 2. car is 1? for Door stand Monty in conditional stand B that has is Door behind situation 1 the condition and for the the has that condition revealed contestant there contestant has is a car chosen Door Analysis that that there has chosen and B is Door a dud behind probability of A (P(A ∩ B)) car Monty The a is behind Hall has problem dud is behind situation can Door to 1 show the and the what is is 1 Door 2 arise in given two that contestant of the the the given Door = 3 has choice because Door 3 2. was when the car is behind Door 1 2 when the car is behind Door 3. of being Door 3. shown This 1 The rst way has a probability of , as shown above. 9 In the Door second 1 or way, Door 2. the If host he is could equally reveal likely either to what choose is behind either of these 1 doors then the probability of showing what is behind Door 2 is 1 × 2 Therefore behind 1 1 + 9 We Door 1 × 2 This the 2 when the of there being contestant revealed has an unwanted chosen Door . is 3 1 18 prize is = 18 P (B), want the the probability conditional of B probability, P ( A | B ) This given by 1 P( A ∩ P ( A | B B) ) = 2 9 = = 3 P(B) 3 18 This means Door 3 that given the that conditional the probability contestant has that chosen the Door car 3 is and behind has 1 been shown that there is an unwanted prize behind Door 2 is . only 3 Therefore Probability it is wor thwhile to switch! . = 9 3 9 is probability Hall using probability chosen ways: 1 monty if 9 probability of conditional 1 × just behind computation 2 3. 3 the Door problem 1 The 3. . Tree Probability diagrams occurs. It is outcomes. ‘With hits is the the problems to to use read different and where these the more than question types of to than list one all carefully the event possible and problems. repeated events that bullseye shot Represent Find the replacement’ probability each for diagrams easier impor tant between Example The useful sometimes It distinguish are tree is is Samuel, 0.8. a hits two b hits only c hits at from information probability keen Samuel independent this a that on takes the a member two the shots. previous tree of school Assume Archer y that Club, success with shot. diagram. Samuel bullseyes one least bullseye one bullseye. The Answers first section of the tree diagram represents Samuel's first HIT shot. He will either hit the bullseye or miss it. The probability 0.8 that he The outcome beside misses the is is 1 – on 0.8 the = 0.2. end of the branch, the probability is branch. 0.2 MISS The 0.8 HIT second There are a hit a hit a miss shot will therefore followed by also four a hit either hit possible (H and or miss outcomes the of bullseye. this ‘experiment’: H), HIT 0.8 0.2 followed by a miss (H and M), MISS followed by a hit (M and H), a miss followed by a miss (M and M). HIT 0.2 0.8 MISS 0.2 MISS a We So b require P(H P(H and and = (0.8 = 0.32 P(H × H) M) + 0.2) + and H). = 0.8 = 0.64 P(M (0.2 × the a hit second product and × Since 0.8 H) 0.8) Only rule). one second These add c P(at least one = 1 – (0.2 = 1 – 0.04 = 0.96 × bullseye) 0.2) two could events, be (H them 1 1 – – shot along either independent and both the the a other hit again 2 and the on and two the (M at events outcomes P(miss getting a hit together with (the branches. first or a hit on the one. M) (as of probabilities top happen (as P(M is multiply the can’t branch need have first can Multiply they each we we the we missing between Here So hit and exclusive: along with shot and the are are bullseye H) same are mutually time. Multiply independent) mutually both and then exclusive). times) M) Chapter Exercise H Correct 1 Lizzie is attempting two exam questions. The probability 2 that she gets any exam question correct is 3 a Copy and b What complete the diagram. Correct 2 is the probability that she will get 3 Incorrect only one of them correct? What is the probability she will get at least c 2 one correct? 2 When Laura 3 and Michelle play in the hockey 1 team the probability that Laura scores and is 3 1 that Michelle scores is . 2 Draw a it to tree find Exam-Style 3 There diagram the are to illustrate probability that this neither information will score in and the use next game. Question equal numbers of boys and girls in a school and it is In 1 known of that the boys and of the girls walk in ever y day . 1 of the boys and of 3 come will in the girls get a there be by the two rst branches section and lift. 2 The rest 3 10 10 1 Also question 1 three branches from coach. each of these in the Determine second the a propor tion come the b 4 by the school population that are girls the school population that come section. who coach, propor tion Determine of the of probability of getting two heads in by three coach. tosses of 2 a biased coin for which P(head) = 3 5 A 10-sided twice. Find the has the numbers probability 1−10 exactly one prime number is rolled, b at one prime number is rolled. least written on it. It is rolled that: a Exam-Style 6 dice Question The probability of Rain a day being windy is 0.6. If it’s windy the Windy probability of of rain is 0.4. If it’s not windy the probability rain is 0.2. a Copy and b What is c What is complete the tree diagram. Rain Probability the the probability probability of of a given two day being successive rainy? days not being rainy? ‘Without Example A bag replacement’ and conditional probability contains 5 green and 6 red balls. If two balls are This taken out successively , probability least without replacement, what is means that the the probability the second of that a at one green is b red is picked on the first pick given that at least one green is chosen? draw is chosen, dependent results draw, of on the since a the rst ball has Answers been Since a red ball has been taken Draw a tree (and 5 there green will be balls) 5 red balls probabilities left section what 5 of on the branches has after diagram. The the initially removed happened rst draw. second depend in the on first R 10 section. R 6 11 5 G 10 6 R 10 5 11 G 4 G 10 a P(at least one green) It = 1 – P(both is quicker probability 6 ⎛ = 1 5 × ⎟ ⎝ 11 10 8 3 ⎞ ⎜ work 11 11 ball on P(red followed by out is green) a the ( red on 1st calculate and at this way the than probability green on both it that is to When the least one green on the second first the pick, pick or a first, the or a green picks. red is probability P in = = 1 ⎠ green b to red) picked of the second being ) 5 = green ( at P least one green is , so multiply these ) 10 probabilities. 6 5 1 3 × 11 10 = 3 2 11 = 8 = 8 8 11 11 Some have tree seen diagrams so do not have the same ‘classic’ shape as the we far. Chapter Example Toby is when is 0.75. him in a he rising gets When winning on 3 out star his he the of 5 of first the school ser ve uses his point. in the second He occasions is Tennis ser ve there successful and Club. probability his at second He that is a that that chance his in found wins 0.45 getting ser ve has he first on 3 point of ser ve out of 4 occasions. a b Find the probability wins the point. Given his that first Toby ser ve that wins the the next point, time what it is is Toby’s the tur n probability to ser ve that he he got in? Answers Win 0.75 On this tree diagram, not necessar y to it is continue the In 3 branches once the point has been Win 5 0.45 0.25 won. Lose In 3 4 2 0.55 Lose Out 5 1 4 a P (win) win) + = b ⎟ + 0.45 = 0.585 P(1st P + ⎝ and in × 5 and get win) ⎞ × 0.45 4 Multiply ⎟ along the branches. ⎠ 0.135 ser ve (1st ser ve ser ve, 3 ⎜ ⎠ = in ⎛ 2 ⎞ × 0.75 ⎝ 5 first first ser ve ⎛ 3 ⎜ (get (miss second Out in|win serve in and point) win point Both ) of these values have been = P ( ⎛ 3 point found ) in par t a ⎞ × ⎜ win 0.75 ⎝ 5 This ⎟ answer has been given ⎠ = = 0.769 (3 to sf) 3 sf as the exact answer 0.585 (fractional) Exercise 1 Three Each is not obvious. I cards card is are drawn not at random replaced. Find from the a pack of probability of playing cards. obtaining See page ordinar y playing a three Probability picture cards b two picture cards. 73 for pack cards. of the 52 Exam-Style 2 A pencil Question case contains 5 faulty and 7 working pens. A boy and Even then a girl each need to take a does a What is the probability that two faulty pens are What c If In is a the exactly the 3 is girl bag one chose are chosen probability 4 at faulty that pen is at least chosen, one faulty what is pen the is chosen? probability that it? red not may balls, 3 green and not question balls and replaced. 2 A yellow second ask balls. ball is A a nd to use to answer these random, the for it chosen? you b if pen. tree it useful diagram some of questions. ball then chosen. 4 a Find P(the balls are both b Find P(the balls are the c Find P(neither ball is d Find P(at one ball Four balls least are replacement, 5 red, 4 blue, Find the 5 A club of the drawn from 3 10 Find b Two the people 6 Billy that you of one after the that the obtain which at chosen Find yellow). the other following and without balls: pur ple. chosen are color). containing 2 probability competition. are is is random, members, members same red). bag orange, probability has a a at green). 6 one are random the at random probability girls to chosen ball be of each and 4 to is represent that are President President one color. of a the One club. boy . the boy boys. club and one in a girl chosen. answers average is 5 on average questions 5 out problems of 9. They correctly both out of attempt 7. the Natasha’s same problem. a b What is the probability answers the question If the that c If the that d If question Billy Natasha was there is the question there that got is got at were that answered correctly , correctly , correct one two? one of the students what is the probability what is the probability answer? answered least least correctly? correct the at answer? correct answer, what is the probability Extension material Worksheet 3 - on CD: Conditional probability Chapter Review exercise ✗ 1 2 A two-digit at random. is divisible c is greater In a class that A this For = Find Explain probability students, is 18 both a at cat is a number? a D ∩ it is ∩ known What a is cat the and 3 have probability dog? D ′) = that: 0.25 P (D) = 0.2. D ′). why C A and and D B are are not independent such that the probabilities P(A) = events. 0.6, P (B) = 0.2 and the of the events occur, c exactly one of the events occur, d B occurs of events that: one given 100 programme, the 18 watch drama 22 watch comedy 35 watch drama 10 watch of than comedy only than write and as an watch drama Using all and which reality , of three they types watch of TV regularly . information: reality reality these as and TV asked comedy; and times reality are types; and none occurred. comedy three only taken has following all three A students 15 watch There are occur, that drama, They provide only , a have 3, 0.1. of is 20 random. least x square dog, and down it: d at If written by both a that is divisible b group inclusive is a A 99 b have selected has and events = and 50, P (C ′ P (C Calculate 5 C b P(A|B) the 10 Questions 0.7 two is between 5, student a The 30 student events P (C ) by than of Exam-Style 4 What a neither. 3 number TV; TV; programmes many two students times as regularly . who many watch who drama watch only U Drama Comedy comedy only . the number expression of for students the who number of watch reality students TV who only . x b the above information copy and complete the Reality Venn c diagram. Calculate Probability the value of x. Review 1 Let P(C ) a Find b Are exercise = 0.4, P(C C P(D) and and = 0.5, P(C |D) = 0.6. D). D mutually exclusive? D independent Give a reason for your answer. c Are C and events? Give a reason for your answer. d Find P(C or e Find P(D D). |C). 3 2 Jack does of the jobs around the house and Jill does the rest. If 5 35% of Jack’s finished house will be a properly , b by Jill if Max The travels for a c What that he he writing the travels travels diagram jour neys in day by by the bicycle, bus bicycle which on by on on shows Monday probabilities probability that he any any the and by of Jill’s jobs around are the and Tuesday , and by iii by the traveled is the on is school probability Wednesday the by to and once by travel that on he in bus is is by car. 0.6. The 0.3. outcomes Label the tree outcome. on does any or on Tuesday , Monday and Monday not Thursday that by bus bicycle and probability car of day or travels Monday method day each Monday same bus Tuesday . on What of done possible on three twice and travel and to Tuesday . school by Friday? days by Tuesday? Max bicycle travels and once car? bag contains into What Without is What passed selects is is is red bag, apples and the green and Tarish. it eats bag, probability Janet is it. she that Without 10 green randomly that Maddy into and Maddy probability red the to two What the the is 6 looking The apple c that each bicycle Max 55% job properly . bicycle The apple is done by looking b a by by a and that ii twice A not school tree is bicycle 4 properly probability i What d to Max’s clearly , b was probability Draw finished the Questions probability a are find done: it Exam-Style 3 jobs properly , it apples. selects one apple. red? Next the randomly is Without bag is passed selects one to Janet. apple. green? replaces looking it in into the the bag. bag, Next he the bag randomly apples. the probability that they are both red? Chapter Exam-Style 5 On a walk carrots female count 23 Venn and a What b What is 70 are rabbits, female diagram eating the is eating Is I and Draw a c Question and and are not hence female, eating find 34 are not eating carrots. the number that are both carrots. probability the 42 that probability a that rabbit a is male rabbit is and female not eating given that carrots? it is carrots? being female CHAPTER 3 independent of eating carrots? Justify your answer. SUMMARY Definitions ● An An A is event an outcome is experiment random over the process is experiment which event from may an by one experiment. which where we there obtain is an outcome. uncer tainty occur. n( A) ● The theoretical probability of an event A is P( A ) n (U ) where ● n(A) and If probability the Y ou The the of to the ways n × is P P, of in event A possible n trials can outcomes. you would times. frequency of that number event occur number to of total an relative the is number is event use larger Venn As n(U) the can frequency ● the occur expect ● is as trials, an the estimate closer the of probability . relative probability . diagrams an event, A, either happens or it does not happen U A P(A) + P (A ′) ● For P (A ′) = any (A ∪ B) 1 − 1 P (A) two = = events P (A) + A and P (B) – B U P (A ∩ B). P(A) P(B) P(A ● In general, if A and B are mutually exclusive, ∩ B) then A P (A ∩ B) = 0 and P(A ∪ B) = P(A) + B P(B). P(A) P(B) Continued Probability on next page Sample space product ● Two ● events other A and of B one two P(A B) events = This is the This is also P(A) are independent does A × not the if affect the the chance that called For two has occurred and B are independent P(B) product Conditional ● the occurs. When ∩ and rule occurrence the diagrams rule the for independent multiplication events r ule. probabi li ty events A can and be B the found probability of A occurring given that B using P( A ∩ B ) P ( A| B ) = P( B ) ● If P ● A ( In and B A| B ′ ) = general given are that P (A) for B independent , two has P ( events, B | A′ ) = events occurred A ( A| B ) = P(A), P ( B|A) = P (B), P (B) and can P B be the probability found of A occurring using P( A B ) P ( A| B ) = P( B ) Chapter Theory of knowledge Probability Math from textbook a bag sur prising People Why the do people chances Asking How do asks a of – rather get lotter y winning the sensitive such tr uth or than problems is as that finding calculating so a real the sur vey headteacher the 600 The interested wants at to know her how school examinations. in probability sensitive by whether is the for she the many relies a She of a winning each are asking student doesn’t just wants an whole knowing know a sensitive harmless to question or a not individual student in If you got a head with overall sur vey ips a the rst ip, question: twice, answer ‘Have cheated in the you an no-one each the honestly. result. asking: They Have they one. school. questionnaire that whether exam?’ student your response ever sends their of showing she on have is specic on headteacher coin If some lotter y? the the estimate relying probability cheated, has balls method Each has colored questions. randomized perfectly in picking question? students cheated abuses odds. This A to national that But probability , What small? involve life? answers when questions from in and often misunderstand tickets are sensitive you useful misuse buy uses probability how uses also intuition – – you ever cheated in school If you got a tail with the follow rst the Yes then exams? instructions ip, answer question: ‘Did the the No on this second card. ip give a tail?’ honestly. she is unlikely to get honest answers. Answer P(Y es to Q1) ‘yes’ 1 p p × = p = 2 Head The tree – Answer question 1 diagram 1 helps P(H) = Answer 2 1 to estimate the 2 fraction p p, Probability ‘no’ = of P(Y es to of answer Q1) Head 1 students P(H) who P(T) have cheated 2 = T ail + answer = 1 p = 2 Answer in an question exam. 1 T ail P(Y es to Q2) = answer 2 1 ‘yes’ × = 2 Theory of knowledge: Probability – uses and abuses 1 1 = 2 4 1 + 2 2 P(T) P(Y es ‘no’ – 4 to Q2) ‘yes’ Suppose 220 ‘yes’ of out students 600 answer The inter viewed. estimated students who number have of cheated in 7 p 1 220 + an exam is 600 = × 140 30 = 2 4 600 p 220 Provided 1 = ever ybody tells the – 2 600 p 4 tr uth when answering their 7 question, this estimates the method = 2 60 number of 7 p = students 30 an Would students answer the who have cheated exam. question honestly? he Probability the and birthday in intui tion truth? – problem people as share the same bir thday? 10%? the rst and Let’s do the math and work it means there are 253 possible pairs of × a pair for pair (Tim, Jane) is students: exactly 23 in choices second. The students 22 out. the 23 person then the same as the 22 = pair 253 (Jane, Tim), so halve 2 the The probability of two people having different bir thdays total. is 364 = 0.997260 365 Ignoring So for 253 possible pairs, the probability that the – two there 365 people in each pair have different bir thdays leap are years 364 bir thdays out that of are is ‘different’. 253 364 ( ) = 0.4995 365 So the have 1 – probability the same 0.4995 Do Are What you = bir thday 0.5005, rely there that, on in areas other the 253 pairs, two people in a pair is 50.05% intuition other about or for to of help – just you over make mathematics areas of half ! decisions? where your intuition has let you down? knowledge? Chapter Exponential and logarithmic functions CHAPTER OBJECTIVES: 1.2 Elementar y 2.6 Exponential Laws of treatment exponents; a of and logarithms; and their graphs and their graphs logarithms change of base x , a > 0, Logarithmic x exponents laws functions x x of log x e functions x, x > 0, x lnx , x > 0 a Relationship x between x ln a these log x functions x a a = e , log a = x; a = x, x > 0 a x 2.7 Solving 2.8 Applications Before Y ou 1 equations you should Evaluate of the graphing form a skills x = and b, a y = b solving equations to real-life situations start know simple of how positive to: Skills exponents 1 check Evaluate 4 e.g. Evaluate ⎛ ⎛ ⎞ a 4 3 3 = 3 × 3 × 3 × 3 = b ⎜ 81 ⎞ ⎝ ⎟ ⎜ ⎠ ⎝ ⎟ ⎠ ⎞ ⎛ e.g. Evaluate 3 ⎜ ⎟ ⎝ c 0.001 ⎠ 2 Conver t numbers to exponential form 2 State e.g. Find n given = 2 the value of n in n n 128 a 7 these equations. n = 343 = 625 b 3 = 243 7 128 = 2 so n = n 7 c 5 2 3 Transform graphs 3 Transform the graph 2 2 e.g. Given the graph of y = x sketch 2 graph of y = x + 3 y 2 y = x + 3 8 6 4 2 2 y = x x –3 –2 –1 0 Exponential 1 2 3 and logarithmic functions the graph of y = (x − 2) of y = x to give the Facebook, the social y media Facebook users 600 giant, celebrated with more up million a Febr uar y than from in 450 huge 200 100 from 0 when 90-ceD 80-ceD 70-ceD million 60-ceD one 300 50-ceD there 400 40-ceD 2004 100 2008 increase December were million about August 500 2010 stinU users, and in sixth )snoillim( bir thday its x members. Dates This graph shows how the (Source: number of Facebook http://www .facebook.com/press/info. users php?timeline) has increased Growth growth. growth the like As this you rate. number over (cer tainly move The of time. growth users until along at the rate that at Febr uar y cur ve any its time 2010) is exponential gradient is increases roughly with propor tional the to time. Chapter A good model for the data on Facebook users is Y ou could also use x n = 1.32 × 1.1 the where n is the number of users in millions, and x is the number model to predictions months after December 2004. the could use the equation n = 1.32 × future 1.1 to estimate the users at any specified date or to find the date at which number of users was ‘extrapolation’. are and as will its you come across opposite, move many other exponential along the examples decay (where of exponential the gradient growth decreases a model to cur ve). Malcolm Imagine again, How Gladwell taking until high 1 Fold 2 For a you do the have sheet number can of this piece folded think fold, folding posed large you each Y ou a the paper (any of layers assume a size) half to The it Tipping over as of many paper of is times the number the paper about 0.1 is The 1 rst × 10 few Number of Number folds of have been done Thickness (km) As thick as a layers −7 0 1 1 × 10 Piece of paper −7 1 2 2 × 10 2 4 4 × 10 3 8 4 16 −7 Credit card 5 6 7 8 9 3 4 How many a as b just How folds thick as taller thick Exponential would the than would you height the the need of a height paper to make the table? of be and a man? after and logarithmic functions 50 folds? paper of possible. folds, formed. km. entries as mm −7 that Point again be? show thickness sheet book folding would in table the his and times. stack this and that in paper , 50 nal complete paper problem of it using this estimate you – with of type future growth? What Investigation the reached. problems Y ou of is a What par ticular This number called of about growth Facebook. x Y ou make of thick, other need factors to do consider? Y ou can probably get to about six or seven folds before you can’t Does fold the paper any more. At seven folds the paper is already about how thick the man. a 50 thick. of a table After folds This Paper 17 is of fact and folds after after it paper about is the an paper sequence In is 15 only folds roughly 13 it folds will 13 m the be paper much thick, is taller roughly depend roughly to big the on star t paper with? Tr y is it. than the height house! the folding layers’ the textbook. two-storey After of this height any of as it as are would distance example for m a be of approximately from the exponential sequence . a function of Ear th the The 113 to the g rowth. ter ms number million of km Sun. The ‘number in folds, n, where n f (n) f (n) In = 2 is an this their exponential chapter inverses, . you growth will which lear n are function more called about exponential functions and functions . logari thmic Exponents Exponents are multiplication a shor thand of a number way by of representing the repeated itself. 5 The expression The 3 in this , 3 for example, expression is the represents base 3 number × 3 and × 3 the × 5 3 is × 3. the exponent. Other names for exponent are power and index 4 It Y ou can also use a variable as the base, for is quicker to write x example, than x × x × x × x 4 x = x × Laws x × of x × x exponents Multiplication 5 5 x 3 x × x = (x × x = x = x Simplify 3 × x × x × × x x × × x x × × x) x × × x (x × × x x × × x) Remove brackets. x 8 5 So x 3 × x (5 + 3) = m ➔ a x n × a 8 = x m+n = a 5 Notice that the two are the Y ou 3 × x variables simplify 3 × y using 5 x base x same. cannot 5 x in , for this 3 × y example, law. 5 = x 3 y Chapter Division Cancel 5 Simplify ÷ x 5 factors. 3 x ÷ 2 x = = 5 So 3 x common 3 x ÷ = x × x = x (5−3) x = x Notice that you 2 = x 5 can’t m ➔ a n ÷ m a = because n to a 5 Simplify 5 (x (x the x 3 ÷ y bases a are Raising simplify not the same. power 3 ) 3 ) = (x = x = x × × x x × × x x × × x x × × x) x × × x (x × × x x × × x x × × x x × × x x) × × x (x × x × × x x × × x x × × x × x) x 15 5 So = (x m ➔ (a 3 5×3 ) = 15 x n = x mn ) = a Example 2 Expand (2xy 3 ) Answer 2 (2xy Don’t 3 ) 2 = (2xy 2 ) × (2xy ) (2xy ) You don’t need to show this line of to working. 3 = 3 2 × x 2 × (y 3 ) 3 = 8x in raise the you have numbers Apply the power of 3 to ever y ter m in bracket to bracket. power as x- y-terms. and well as the the A Simplify 1 3 2 x a × 2 x b 4 3p × 2p 2 q c × 3 d (x 2 y 4 )(xy ) Remember to multiply the constants Simplify 2 5 2 x a ÷ 7 x b 2a 3 ÷ 2a 7 c 2a (2a) well Simplify 3 (x a The 4 2 ) b power 3 ) 3 c 3(x zero 2 Simplify (3t 2 x ÷ x = = = But 0 Therefore x = Exponential 1 and logarithmic functions together as d 3 (numbers) 3 ÷ the 6 y the Exercise forget 2 × 2 y 2 ) 2 d (−y 3 ) as the variables. 0 ➔ a = ‘Anything 1 Any base raised to the power of zero is equal to zero 1. is ‘Zero Fractional is to 1. ’ power 0. ’ 0 So × what How decide Who we ? should 0 what about + Law any But equal to power Using the exponents Simplify to this is equal should to? decide? so = Similarly and and so Y ou can assume always that a ➔ = is positive when considering Roots of 2 = 2 x a. 6 x roots Simplify Since even × 2 x × = x 2 = x 6 3 = x ➔ = Example ( ) = ( ) = ‘Evaluate’ Without using a calculator, means evaluate: 4 ‘work out the value 1 ⎛ 1 ⎞ 3 2 a 36 b ⎜ ⎝ of ’. ⎟ 27 ⎠ Answers 1 1 2 a 36 = 36 = n 6 Since n a = a 4 4 1 ⎛ ⎛ b 1 ⎞ 3 ⎜ ⎞ ⎛ 1 ⎞ 3 ⎝ ⎟ 27 ⎠ ⎜ ⎜ ⎝ ⎝ 27 n m ⎟ = ⎜ Since ⎟ ⎟ ⎠ ⎠ (a mn ) = a 4 1 ⎛ ⎜ ⎟ 3 ⎝ ⎞ 27 ⎠ 4 ⎛ 1 ⎞ ⎜ ⎟ ⎝ 3 ⎠ 1 81 Chapter Negative exponents 3 Simplify 5 x ÷ x 3 x 5 ÷ x = = × = 3 Also 5 x ÷ x 3−5 = −2 x = x And therefore = Y ou ➔ must learn the = laws as for they exponents are Formula Example Without using a calculator evaluate 2 ⎛ −2 a 6 3 ⎞ b ⎜ ⎝ ⎟ 4 ⎠ Answers 1 1 1 n 2 a 6 = = Use a = n 2 a 36 6 2 ⎛ b 3 1 1 ⎞ = = ⎜ ⎝ ⎟ 4 2 ⎠ ⎛ 3 ⎜ ⎝ ⎞ ⎟ 4 ⎠ ⎛ 9 ⎜ ⎝ ⎞ ⎟ 16 ⎠ 16 = 9 Exercise ✗ 1 B Evaluate 2 1 1 3 3 2 a 9 b 125 c 64 2 2 ⎛ 8 ⎞ 3 3 d 2 8 e ⎜ ⎟ ⎝ 27 ⎠ Evaluate −3 a 2 b c ⎛ d ( ) ⎞ e ⎜ ⎟ ⎝ ⎠ Exponential and logarithmic functions not in booklet. the Example Here Simplify these expressions. ‘simplify’ 1 2 0 −3 5d a 2 6x b ÷ (2x 3 3 ) ⎛ 6 27 a c d ⎞ 9v ⎜ ⎝ 2 means write these ⎟ 4 expressions 16w using only ⎠ positive exponents. Answers 0 0 5d a = 5 × 1 −3 2 6x b = ÷ (2 x 5 Use 3 −3 ) = a = m 6 6x ÷ 8x 6 1. (a Use n ) mn = a . 3 9 m = x = Use a n ÷ a m = – n a 9 8 4 x 1 1 1 1 3 6 6 = ( 27 a = 27 ) n 6 3 3 27 a c ( m m n 3 a a Use ) = (a ) . 2 = 3a 1 1 2 ⎛ d ⎜ ⎝ 4 2 ⎞ 9v 4 16w = ⎟ ⎠ ⎛ 16w ⎞ ⎜ ⎟ ⎝ 2 9v 2 1 n a Use = n a ⎠ 1 4 (16w 2 2 ) = 4w = 1 3v 2 (9v Exercise C Simplify 1 2 ) these exponential expressions. In this exercise, ( a ) b c d make sure your e answers have positive exponents. Simplify 2 these expressions. a b ÷ c . Solving Exponential exponential equations are equations equations involving ‘unknowns’ x as exponents, for example, 5 = 25. y x Y ou can write Example 3 exponential equation in the form a = b x –1 Solve an 5x = 3 Answer x 1 3 x 5x = − 1 = 3 Both 5x sides powers of of 3 the so equation the two are exponents are equal. −1 = 4 x 1 x = − 4 Chapter Example 3x Solve + 1 For 3 = this many of the questions Answer 3 x +1 3 example = to 81 learn 3 x +1 2 4 = Write 3 81 as a power of 1 = 1 = 3 = 9 1 = 2 3 = 4 3 exponents. 2 = 3 2 3 2 x powers. 4 2 3x 3 3. 2 Equate + 1 = need 0 = 1 3x following you these 0 3 and 81 3 = 8 3 = 16 3 = 32 3 = 64 = 128 = 1 7 = 5 7 4 = 1 2 5 2 = 27 = 81 = 243 = 1 = 7 4 5 6 2 Exercise D 7 2 Solve 1 these equations for x 0 5 x ✗ 1−2x 2 a = 32 3 b 1 = 243 5 1 2 2 x 2 x 5 2x−1 3 c 0 = 27 5 d − 25 = 2 = 25 7 = 125 7 = 625 3 5 x 4 = 5 49 Solve 2 these x−3 3 a equations for 2−x = x 3x 3 b 5 d 2 x−2 = 25 + c 2−3x = x−1 = 4 EXAM-STYLE QUESTION + Solve 3 Example = 3 5 Solve 3x = 24 Answer 3 Divide both sides by 3. 5 3x = 24 3 Multiply 5 x the exponent a reciprocal 5 since − 5 x ) 3 = 8 5 3 Replace 3 x = x = ( ) 2 3 −5 2 1 x = 32 its Exponential and logarithmic functions 8 with 2 b × b 5 3 ( by =8 3 49 343 3 1 1 7 e = = 0 = 1 − a Exercise Solve 1 E these equations for x 4 5 2x a = 162 x b − −2 c x = e 27x 16 d 8x Solve = 0 f 27x 3 = −2 2 32 −3 (8x) −3 = 81x these equations for = 64 x a = b c = = d = e = f = Solve 3 these equations for x 3 2 x a = 125 b = c . = 192 and d Exponential Graphs ➔ 216 = 16 functions properties of An exponential function is a exponential function of the functions We form could also write x f : x → a x f (x) where = a a is a positive Investigation Using a GDC, sketch – real number graphs the graphs of (that of is, a > 0) and exponential these exponential a ≠ 1. functions 1 functions. Think about the x a y = 3 b y = 5 domain, range, x intercepts on the x y c = axes, 10 asymptotes, shape Look at your three each What can you and behavior of graphs. deduce about the exponential graph as x tends function, to innity. x f (x) = a , Whatever when a > positive 1? value a has in the equation y x f (x) = x , the graph will a always have the same f(x) = a shape. x f (x) = a is an exponential growth function 1 (0, 1) 0 x Chapter x ➔ The domain The range The cur ve The graph value of x of is f the does (x) = set a of not is all the of positive intercept approaches set the closer all real real numbers. numbers. x-axis. and closer to the x-axis The y-intercept The graph is of f passes through the points ⎞ , − ⎜ ⎝ (1, The Now between at 0 increases the and graphs a 1) ⎠ GDC exponential continually . of exponential functions when the base a is 1. Investigation Using (0, ⎟ a). graph look the 1. ⎛ and as decreases. sketch - the graphs graphs of of exponential functions these functions. –x y a = −x 3 y = 3 is the –x b y = 5 c y = 10 1 equivalent of y or = x –x y –x What can you deduce about the exponential function, f (x) = a a > 1, from these three graphs? −x Whatever will positive always have –x f(x) = value this a has, the graph of shape. y a (0, 1) 1 0 x – x f (x) = a is an Exponential exponential decay and logarithmic functions function f (x) = a = ⎛ 1 ⎞ ⎜ ⎟ ⎝ 3 ⎠ so the base , is when 3 x between 0 and 1. The The natural base e is exponential exponential one that you you come across often in functions. Investigation When will function invest – money compound it earns interest interest. n t r ⎛ We use this A = C formula ⎜ r is of the is the nal interest happens £1 a is if in you invested How much (capital expressed a at will year , star t an and as t + a is interest), decimal, the total compounding interest you calculate the interest, n ⎠ amount rate compoundings What 1 A to ⎟ ⎝ where ⎞ 1 + have rate if this of is is the the number more 100% is n C and for capital, number of years. more 1 frequently? year . compounded year ly? 100 P = 1, r = 100% = = 1, n = 1, t = 1 and n = 100 1 1 ⎞ ⎛ A = C ⎜ 1 + b How C = ⎟ 1 ⎝ much 1, r = = 2 (since r = 1 1) ⎠ will you 100% = have 1, n if = this 4, t is = compounded quar terly? 1 4 1 ⎛ A = ⎜ 1 + 2 Copy and ⎟ 4 ⎝ ⎞ = 2 44 140 625 ⎠ complete Compounding the table. Calculation F inal all amount gures on (write calculator) 1 1 ⎞ ⎛ Y early ⎜ 1 + 2 ⎟ 1 ⎝ ⎠ 2 1 ⎛ Half-Y early ⎜ 1 + ⎟ 2 ⎝ ⎞ 2.25 ⎠ 4 1 ⎛ Quar terly ⎜ ⎝ 1 + ⎞ ⎟ 4 2.44 140 625 ⎠ Monthly Weekly Daily Hourly Ever y minute Ever y second Chapter The final amount compoundings smaller value The and is value of impor tant subject e is an the called increases decreases final as but amount the inter val each between separate converges on increase a value. is This ‘e’. e is approximately number in 2.71828 mathematics and which it has is an exceptionally applications in many areas. number. irrational Jacob Bernoulli (1654–1705) Mathematics beautiful sometimes throws out some surprising one and is one results. such 20 decimal Swiss is no places e = 2.718 281 828 459 045 235 obvious pattern to this chain of look at this series, which gives a 1 1 + value 1 + of 2 × 1 3 × 2 × 1 the tried to nd 4 × 3 × 2 × 1 1 ⎞ ⎛ + ... of ⎜ 5 × 4 × 3 × 2 × 1 tends might [See and the wonder Theor y discussion about of on the connection Knowledge beauty in page at between the end this of series this and chapter the for value of 1 + to thoughts used of the exponential function f (x) = e is a graph growth is the exponential binomial and the graph of f (x) = is e limit to a show had 2 to and considered that lie 3. to This be graph the of He of x exponential innity. between x graph n ⎠ mathematics.] the The as ⎟ n e. theorem ➔ the n + ⎝ Y ou problem interest, e: limit 1 at compound 1 + was numbers. he 1 e = 1 + he 36… of However of Bernoulli When looking There great result. family. T o the mathematicians the Here of was rst approximation decay . found y for e. y x f(x) = e –x y = e An (0, 1) (0, 1) x 0 Transformations Now you function, Chapter know you 1 to the can help Exponential of exponential general use you the x 0 shape r ules sketch of for graph of an transformations graphs and logarithmic functions the functions of other exponential of graphs exponential from functions. number cannot be expressed exactly as a a 1 irrational decimal. fraction or ➔ f (x) ± units k translates ver tically up f (x) or through k y down y f (x ± units or k) translates horizontally f (x) to through the y k = = f(x (x) (−x) pf + 2 f(x) + 2) right reflects f (x) in the y x-axis y f f(x) left y −f = (x) reflects f stretches scale factor f stretches (qx) (x) f in (x) the f(x) f(x) –f(x) y y-axis ver tically = = = = f(–x) y with = y y (x) f(x) 2f(x) p f = = f(x) horizontally y = f(2x) with scale y factor = f(x) Example x The diagram shows the sketch of f (x) = y 2 x−2 On the same axes sketch the graph of g (x) = 8 2 6 4 2 x 0 –3 –1 1 3 Answer y 8 You find f through (x) g (x) by 2 translating units to the right. 6 4 The graph of 2 the (0, 1) point ⎜ 0, ⎝ –1 will pass through ⎞ ⎟ 4 ⎠ x 0 –3 g (x) 1 ⎛ 1 3 4 5 Both graphs get closer and closer to 1 4 the x-axis as the value of x decreases. Chapter Exercise 1 Given the F the graph graph of intercepts of g (x) on the on f (x) = (x), and the axes x a f without same and set any of using axes a calculator, showing g (x) = x 2 + 3 b f (x) = g (x) 8 8 6 6 4 4 2 2 x –1 1 1 –4 –4 –6 –6 –8 –8 –10 –10 ⎜ ⎝ ⎞ x = ⎟ ⎜ ⎠ ⎝ d ⎟ f (x) = x+1 e g (x) = e ⎠ y y 8 8 6 6 4 4 2 2 x 0 –3 3 ⎛ ⎞ = x –1 –2 3 0 –3 3 –2 ⎛ = y 0 c any –x 3 y –3 clearly asymptotes. x 2 sketch –1 x 0 3 –3 –1 1 –2 –2 –4 –4 –6 –6 –8 –8 –10 –10 3 2x x ⎛ ⎞ e = ⎜ ⎝ ⎟ = f ⎜ ⎠ ⎝ f ⎟ ⎛ 1 ⎞ ⎛ 1 ⎞ ⎛ ⎞ ( x ) = ⎜ ⎝ ⎠ y g ⎟ e ( x ) = ⎜ ⎝ ⎠ ⎟ e y 8 8 6 6 4 4 2 x 0 –3 2 State –1 the –3 –1 –2 –4 –4 –6 –6 –8 –8 –10 –10 domain Exponential and range x 0 3 –2 of each g(x) and logarithmic functions function 1 in 3 question 1. ⎠ . Properties of logarithms 3 Look 2 is So at the we this equation: base say 8 and that = 3 the is 2 the = 8 exponent logari thm of 8 or logari thm to the base 2 is 3 and write this 3 as log In general, 2 given that a > 0: x ➔ If b = a then log b = x a or, Being if b is able simplify to log Example Evaluate a to the change power x, between then x these is the two logarithm forms of allows b, you to base a to statements. log 125 5 Answer Write x = log ‘x =’ the log statement. 125 5 x 5 Change = 125 = 5 = 3 x 5 x Equate 3 Example Evaluate equation to exponent for m. exponent for m. exponents. log 4 64 Answer x = log 4 64 x 64 = Change 4 equation to 3 3 (4 x ) 3x x 1 = 4 Write 64 = 1 Equate 1 and as the solve 4 exponents for x. = 3 Exercise ✗ 1 G Evaluate a these expressions. b 2 c Evaluate these log 64 d 2 expressions. 1 a log b 3 c d 81 Chapter Example Evaluate log 4 4 Answer Write x = log ‘x =’ log statement. 4 4 Change equation to exponent x 4 = 4 = 1 for m. x 1 Equate In general, ➔ log a the = log to base a of any exponents number a = (4 = 4 ). 1. 1 a Example Evaluate log 1 5 Answer x = log 1 5 x 5 x = 1 = 0 Any any Write number base ➔ log is 1 raised to the power 0 is equation equal to 1 in so exponent the log of 0. = 0 a Exercise ✗ 1 H Evaluate log a 6 log b 6 log d 1 log e 8 Some you 1 log What log c find are solutions 1 log f happens when 1 b undefined for n n 2 expressions can’t 10 10 – this means that them. you tr y to evaluate the expression (−27)? log 3 First write x = the log log equation. (−27) 3 Then rewrite the equation in exponent form. x 3 This −27 equation Y ou ➔ = can log b is only has find no solution. logarithms undefined for any of base a Exponential and logarithmic functions posi tive a if b is numbers. negative. for m. 1 in What 2 is the value of log 0? 3 First write x = an log equation. 0 3 Rewrite in exponent form. x 3 This ➔ = 0 equation log 0 is has no solution. undefined. a Example 13 Example illustrates another proper ty of logarithms. 5 Evaluate log 2 2 Answer Write 5 x = log log equation. 2 2 Rewrite x 2 in exponent for m. 5 = 2 = 5 Solve. x n ➔ log (a ) = n a Summary Given that a of > properties of logarithms 0 b ● If x = a then log x = b a ● log a = 1 a ● log ● log 1 = 0 a b is undefined if b is negative a ● log 0 is undefined a n ● log (a ) = n a Example Find the value of x if log x = 5 2 Answer log x = 5 = x Rewrite = 32 Solve. 2 5 2 x Exercise 1 Write 2 x these = Write a x equations in log for m. form. 5 2 b these = exponent I 9 a in log 2 8 x = equations b x = 4 3 in c exponent log 3 27 c x = b 10 d x = a d x = log form. x = log 10 1000 b a Chapter Solve 3 these log a x = equations. 3 log b 4 x = 4 log c 3 64 = 2 x log d 6 = log e x x = −5 2 . Logarithmic functions Investigation – What would kind of function inverse undo functions an exponential function x such f as : x 2 ? x Copy a and complete this table of values for the function y = 2 x x −3 −2 1 0 1 2 f : 3 f x is ↦ a 2 means function that under 1 which x is mapped y x 8 to 2 x The inverse y-values Copy b and and function switch complete of y = 2 will take all the x- and for the inverse them. this table of values x function of y = 2 . 1 x 8 y −3 x Using c and its What d Now ➔ you find find and tables inverse do let’s To these then values function on sketch the a same graph set of of both y = 2 axes. notice? the an of equation inverse of rearrange a to of the graph function make y of the inverse algebraically , the function. switch x and y subject. x f : x 2 is another x −1 To get the inverse function, f , of way of writing y = 2 : x Write y = 2 y is the exponent that y x log = 2 Switch x = ylog y = log 2 so 2 Take x and logs to y the the base 2 of both sides by base in 2 order Since log 2 = 2 Log is shor t logarithm. ➔ Generally if then x y = log x is the inverse of y = a a get 1 to raised 2 x 2 So is Exponential and logarithmic functions for x x The graph of y = log x is a reflection of y = x a y y = a a in the line y = x y = x = log (0,1) y x a x (1,0) ➔ A logarithmic function, f ( x) = log x, has these John proper ties: Napier (1550– a 1617) the domain is the set of all positive real much the range is the cur ve does the set of all real intercept of the y-axis is a ver tical the x-intercept on logarithms. you graph is continually Transformations of Again the once you logarithmic to consider the Exercise 1 Given know function that he logarithms or 1 discovered the say asymptote invented is with early y-axis Would the credited the numbers work not is numbers graphs increasing. logarithmic you general can of them? use other shape what functions of you logarithmic the graph lear nt in of a Chapter 1 functions. J the function f ( x) = log x y describe a the transformation required in each case y = log x a to obtain the graph a g ( x) = log b g ( x) = log (x) − of g(x) 2 a 0 x (1, 0) (x − 2) a c g ( x) = 2log x a EXAM-STYLE 2 Sketch the QUESTION graph of y = −2log(x − 1) without using a calculator. When Include on your graph the intercepts with the two the (if 3 they Sketch exist). the of y = log (x + 1) + 2 clearly base logarithms base graph no is given axes labeling are 10. any 2 asymptotes 4 The sketch on the shows graph. the graph of y = log x. y a Find the value of (27, 3) a 0 (1, 0) x −1 5 Given that f (x) = log x find f (2) 3 Chapter Logarithms to base x y = log x is the inverse of y = 10 . This is an impor tant logarithm 10 as it is Base and one 10 of logs just the are write only ones called log x for that you common log can logs use and the you calculator can omit the to find. base x 10 There is a ‘log’ Example Use a key on the calculator. calculator to evaluate log 2 to 3 dp. Answer log 2 = *Logarithms 1.1 0.301 to 3 log dp. 0.30103 (2) 10 GDC help on CD: demonstrations Plus and Casio Alternative for the TI-84 FX-9860GII 1/99 GDCs Natural The are on the CD. logarithms logari thm , natural log x (log to the base e), is the other e impor tant Y ou write logarithm. ln x for log x. There is an ‘ln’ key on the calculator e Example Make ln 4 Use a calculator to sure you close evaluate the ln 2 brackets after the 4 the calculator otherwise Answer ⎛ calculate = 2 will *Logarithms 1.1 ln 4 In(4) ln 4 ⎞ ⎜ ⎟ ⎝ In 2 ⎠ 2. ln 2 In(2) GDC help on CD: demonstrations 1/99 Plus and GDCs Exercise 1 K Use a to significant a 3 calculator log 3 to evaluate 4log 2 correct c e f (log 3) Exponential 2 h log 2 expressions figures. b d g these log 3 and logarithmic functions Casio are on Alternative for the TI-84 FX-9860GII the CD. ➔ y = ln x is the inverse of the x exponential function y = e x y y = e y = x (0, 1) y = In x x (1, 0) This relation gives us x ➔ log (a three log ) = x and results: x a a impor tant = x a x ln(e lnx ) = x and e = x log (10 Solve log x ) Example x = x and (10 ) = x these equations, giving your answers x e a to 3 significant figures. x = 2.3 ln x b = –1.5 c 10 = 0.75 d log x = 3 Answers x e a = 2.3 x ln(e ) = ln2.3 x = 0.833(3 sf) Write in natural log for m. x b ln x = –1.5 = e = 0.223(3 sf) lnx e x Use ln –1.5 (e ) Use (e ) = Use log(10 Use 10 x 10 c = x and evaluate. lnx x and evaluate. x = 0.75 ) = log 0.75 x = −0.125(3 sf) ) = x and evaluate. x log(10 log x log x d = 3 log x 10 x = x and evaluate. 3 = 10 = 1000 Example 1 2x Given that f (x) = e , −1 find f (x). 3 Answer 1 2x f (x) = e 3 1 2x y = e 3 1 2y x = e Interchange x and y. 3 { Continued on next page Chapter 2y 3x = e 2y ln(3x) = ln e ln(3x) = 2y x Use ln(e ) = x. 1 ln(3x) = Solve y for y. 2 1 –1 So f (x) = ln(3x), x > 0 2 Exercise 1 Solve L these equations giving x a e d e answers to 3 sf where x = 1.53 x e b necessar y . = 0.003 e c = 1 x x = 5e e = 0.15 2 Solve these equations giving answers to 3 sf where necessar y . x x 10 a = 2.33 x 10 b = 0.6 10 c x = 1 d 10 = 3 Find if log x a 4 x = Without log 2 log x b using a 5 −1 calculator 12 log 5 log x c evaluate 4 5 b Without using a 0 d evaluate log x = −5.1 expressions. ln4 c calculator = these 5 5 a = d these e expressions. 5 ln e a log 100 b ln1 c ln e d e ln EXAM-STYLE QUESTIONS 2x−1 6 Given that f (x) = e 7 Given that f (x) = e −1 find f (x) and state its domain. 0.25x , −2 ≤ x ≤ 4, state the domain and −1 range of f −1 8 Given that f (x) = ln 3x, 9 Given that f (x) = ln(x x > 0, find f (x). x − 1), x > 1, and g(x) = 2e find (g f ° . We Laws can of deduce logari thms the laws of logarithms p equations, x = = a q and y = and = a then = and = and so = × = = + = + and hence Exponential + and logarithmic functions from the exponential )(x) This equation is tr ue for logarithms in any base so Notice ➔ log x + log y = log that xy log xy ≠ log x × log y x = ÷ = and that log log x log y ≠ y so = − and hence = − x ➔ log x – log y = log y = = so = and hence = n ➔ We n log can x = also log x derive this ➔ key result from the third law . −1 × = − All can these be laws are omitted. Formula tr ue Y ou for must logarithms lear n these in any laws base as and they are so the not in bases the booklet. Example 1 Express log 5 + log 2 36 2 log 10 as a single logarithm. 2 2 Answer 1 log 5 + log 2 36 log 2 10 2 2 1 n 2 = log 5 + log 2 = log 36 log 2 5 + log 2 10 n log 6 2 log 30 2 = log x a 10 2 log x = log x a 2 log + log y = log xy 10 2 x = log 3 log x log y = 2 y Chapter Exercise 1 M Express as single logarithms: a b log 24 e 3log – log 2 c 2log f log 8 – 4log 2 d x – 2log y x – log y – log g 2 Express + as single − logarithms: a − b c − 2ln3 d – ln18 e 3ln2 – 2 f 3 Find the a value of each expression log b (each 24 – answer log 2 is 3 an c integer). 2 d e Example Given that a = log x, b = log 5 ⎛ log write 5 in ⎟ 2 y and c = log z, 5 ⎞ x ⎜ ⎜ y 5 3 terms of a, b and c log z ⎟ z ⎝ ⎠ Answer ⎛ ⎞ x 2 log 5 ⎜ = ⎟ 2 ⎜ y 3 log x log 5 y 3 z 5 ⎟ z ⎝ ⎠ 1 x log 3 2 2 = y (log 5 + 5 ) 5 1 = log x − 2log 5 y − 3log 5 z 5 2 1 = a − 2b − 3c 2 Exercise N EXAM-STYLE 1 Given that QUESTION p = log a and q = log 2 of p and/or q b, find an expression 2 for: 3 a log ab b 2 log a c d e Exponential 2 and logarithmic functions in terms z Let 2 x = log P, y = log Q and z = log R. ⎛ Express Write these where a in ⎟ ⎝ 3 ⎞ ⎜ terms expressions and b of x, y and z ⎠ are in the form a + blog x integers. log10x a b c d EXAM-STYLE QUESTIONS Given 4 that write y in the form y = pa + q where p and q are integers to be found. Write 5 in the form a + blog x where a and b are 3 integers. x xln2 Show 6 Notice that that e = 2 question 6 in Exercise 4 N demonstrates the general result x a xlna = e Change of Sometimes there is a Suppose base you need formula y = log to that a change enables and you the you want base to to do of a logarithm and this. change the log to base c. b y If y = log a then a = b b y Star t with a = Take logs to b base c of both sides: y log a = log a = ylog c log b c c b c = But y = log a so b ➔ Change of base formula: This = formula is useful as most only Y ou can use this formula to evaluate a logarithm or to logarithm to any calculators logs to base change 10 a give or e. base. Chapter Example Use the change of base formula to evaluate log 9 to 3 4 significant figures. Answer log 9 log 9 For = Change 4 the log to base 10 = 1.58 (3 sf) Use calculator to evaluate answer. Example log 3 = a and log x 6 = b. x Find log 6 in terms of a and b 3 Answer log Use 6 the change of base for mula. x log 6 = 3 log 3 x b = a Exercise 1 O Use the to significant 3 change of base formula to evaluate these expressions figures. ⎛ ⎞ a log 7 b ⎜ c ⎟ log 2 (0.7) 3 ⎝ ⎠ 7 d log e log e 7 2 Given 7 3 that log x = y, express log 3 EXAM-STYLE 3 If log 2 log = d log x and log 6 a y log 24 e log y, find Given terms c log 12 f log of y of x and 6 GDC log to x sketch b y = that 36 2 3 2 these 2log 4 5 in 2 6 your = = b a Use terms a 6 2 4 in QUESTION a a x 9 graphs. x 5 log a = b express y in terms of b 4 2 a y = log a b y = log 4 a 16 c = Exponential and logarithmic functions d = y: base 10 logs, 10. log 4 is omitted. the . Exponential Solving Y ou In can exponential use Section numbers you are will and logarithms 4.2 you were the lear n to solved same how to logari thmic equations solve exponential exponential or equations could solve be equations made equations equations. the where where same. the In base the this base section numbers different. Example x Solve 5 = 9 Answer x 5 = 9 = log 9 = log 9 Choose base 10 or x log x log 5 5 log 9 x Take logs of Now bring Rear range both down the sides. the natural exponent. you logs can use so that your GDC. equation. = log 5 x = 1.3652… x = 1.37 (3 sf) Check an Example 6 question requires ln a x + 1 = the answer x Solve whether exact 3 giving your answer in the form ln b where a and b are integers. Answer x x+1 6 = 3 x ln 6 x ln 6 − x +1 = x ln 6 = (x x ln 6 = x x ln 3 x (ln 6 − ln 3) = = Take ln 3 + 1) ln 3 ln 3 + ln 3 natural Bring down Multiply Collect ln 3 the out of both sides. exponents. brackets. x-ter ms Factorize ln 3 logs and together. divide. ln 3 x = (ln 6 ln 3 ) a ln 3 x ln a = ln 2 − ln b = ln b Chapter Example 3x Solve 1−x e = 5 , giving an exact answer. Answer x 3x = x (3 = ln 5 3x = (1– 3x = ln 5 x ln 5 + logs since ln e = x 1 – x ln e + natural 5 3x 3x Use 1 – x e x) = ln 5 = ln 5 ln 5) – ln 5 Bring down the exponents. x ln 5 Multiply Collect out Leave brackets. x-ter ms in together. log your form answer since ln 5 Factorize x and an divide. (3 + ln5) Exercise 1 Solve required. P these equations x to find the value of x to x 2 a = 5 b 3 f 2 3 significant x = 50 c 5 g e figures. x+1 = 17 7 d = 16 2x−1 Solve = 3.2 × x 10 = 6 h = EXAM-STYLE 2 −3 e QUESTION these equations to find the value of x to 3 significant figures. x+2 x −3 2x −5 2−x a 2 e e = 5 = c 3 4e f 7 d = x −1 = (0.5) −0.001x 3x −2 x = 4 x + 3 b 3x −1 Example = 244 g 35e = 95 ln a x −1 x+2 Solve 3 × 6 = 2 × 3 , giving your answer in the form x , = ln b where a, b ∈ Answer x ln (3 × – 6 + ln (6 1 x + 2 ) x ln 3 = ln (2 × 3 – 1 ) Take + ln 2 + + (x – 1) ln 6 = ln 2 ln(3 + (x both + + x ln 6 x ln 6 x(ln 6 – – ln 6 xln 3 – ln 3) = = = ln 2 ln 2 ln 2 + + x ln 3 ln 9 x-ter ms 2)ln 3 2ln 3 + sides. ) and ln 3 logs 2 of = natural ) x Collect ln 3 + + + factorize. 2ln 3 ln 6 ln 6 – – ln 3 ln 3 ⎛ 108 ⎞ ln ⎜ You ⎟ ⎝ x 6 ⎞ simplify ln a = ⎛ ln 2 fur ther this ⎟ and logarithmic functions a – ln b ⎜ ⎝ 3 ⎠ Exponential can’t ln 36 ⎠ 3 = ln exact = ln b any answer is Exercise Q EXAM-STYLE 1 Solve QUESTIONS these equations to find the value x a d 5 = x – 1 2 × Solve b 4 e 3 x 2x 2 = these 3 × × 7 equations to find 3 of x the 3 significant = figures. x 5 3 c x – 1 4 to 2x – 1 × 2 x = 4 × 5 x + 2 = 2 × value 7 of x in the form , = where a, b ∈ x + 2 a 2 c 5 x – 3 = x 5 3 Solve = 2 × 6 (6 b 4 − Solving = x – 8 × 7 1 )(2 x + 2 ) x Some d x 3 = 2(4 ) x a × 3 – 2x 3 for 5 x x + 1 × b = logarithmic logarithmic x – 3(2 ) = 0 equations equations can be solved by ensuring that both The sides of the equation contain logarithms written to the same argument expression Then you can equate the is the base. inside the arguments brackets. Example 2 Solve log (x ) = log a (3 x + 4) a Answer 2 (x log ) = log = 3x 4 = 0 1) = 0 a (3x + 4) a 2 x + 4 Equate the arguments. 2 x (x − − 3x 4)(x x = Y ou − + 4 or x you Substituting the log Example Solve x that both cannot = of the quadratic. −1 check must Remember gives = Solve 4 a and solutions find x = positive the −1 are possible. logarithm into number both so of sides here a negative of both the number. original solutions are equation possible. ln(12 − x ) = ln x + ln( x − 5) Answer ln(12 − x) = ln x ln(12 − x) = ln x (x + ln(12 − x) = ln(x = x ln(x − − 5) 5) 2 − 5x) 2 12 − x − 5x Equate arguments. 2 x (x − − 4 x 6)(x x = 6 − + 12 2) or x = 0 = 0 = −2 Solve the quadratic. { Continued on next page Chapter When ln x When ln x so x = and x = and x = Check 6 ln(x 6 − is − the 5) are only solution. equations = − − b d + = − − it Example log (x is − + + = − = to solve a + log equation using Since = exponents. 3 5 Answer log (2x – 1) = 3 5 3 b 5 = 2x – 1 log x b ⇒ x = a a 125 = 2x = x Example Solve 2x – 1 126 = 63 log x + log 2 (x − 2) = 3 2 Answer x log + log 2 (x − 2) = 3 2 [x (x log − 2 )] = 3 2 Using the first law on page 2 (x log 2x ) = 3 2 2 x 3 − 2x = 2 b Since log x = b ⇒ a 2 x − 2x = 8 2 x (x + 2 )( x x x = − 2x 4 = −2 is Exponential − 8 − 4) or the x = 0 = = only 0 4 solution and logarithmic functions x must be positive. x = a = easier 2) Sometimes Solve x. e for c negative QUESTION these a solutions. positive. R EXAM-STYLE Solve are −2 ln(x Exercise 1 5) 123. + Exercise Solve 1 these log a S (x equations − 2) = 2 for x. log b 9 (2x − 1) = 3 c − = 3 Solve 2 these a equations − + log c (2x − 3) – (4x − 8) – log log (4x − 5) = (x − 5) = 4 2 0 QUESTIONS that an Hence log b 2 x + find 7 EXAM-STYLE Given = x. 7 3 for expression or x + = for otherwise A A in solve terms log x of + x. log 2 (2x + 7) = 2 2 Y ou will change Solve 4 + need the to base here = rst. Solve 5 + . = Applications of exponential and Extension material Worksheet 4 linear logarithmic Exponential Models of exponential and growth and decay functions. areas just a few applications of exponential of appear mathematics to decay be completely growth disconnected and to form use that are CD: decay T wo Here on Reduction functions growth exponential - might be exponentials models. and probability. Biology But ● Growth ● Human of micro-organisms in a consider A Spread problem… group of people go to lunch and population afterwards ● this culture of a pick up their hats at virus random. What is the probability that Physics no ● Nuclear ● Heat chain one gets their own hat? reactions It can be shown that this probability transfer 1 is . Economics Y ou ● Pyramid Processing power e to one of you the basis have like to studied explore this probability once fur ther .) of of Can your might these technolog y as ● wish (Y ou pick Computer may schemes you think of any other areas Mathematical computers of knowledge that are surprisingly Exploration. ● Internet trafc growth connected? Chapter Exponential Example The growth population, A(t ), in thousands, of a city is modeled (0.02)t by of the function years after A(t ) 2010. = 30e Use where this model t to is the number answer these questions: a What b By was what each the population percentage is the of the city in population 2010? of the city increasing year? c What d When will the will population the city’s of the population city be be in 2020? 60 000? Answers t 0 a A(0) = 30e = 30 is so The population in 2010 the for number 2010, t = of years after 2010, 0 was 30 000. (0.02) b A(1) = Write 30e one ( 0.02 ) an year equation after for the population 2010. 30 e ( 0.02 ) = e Calculate the multiplying factor. 30 = 1.0202... The at population 2.02% each is increasing year. In 2020, t = 10 ( 0.02 ) ×10 A(10 ) c = = In 30e 36.642... 2020 the population will be 36 642 ( 0.02 ) t d 60 = 30e When population is 60 000, ( 0.02 ) t 2 = A(t) e Take ( 0.02 ) t ln 2 = ln e ln 2 = 0 .02t = 60 logarithmics Bring down ln 2 t = Solve 0 t The after = 34.657... population 34.65 during 02 will years, be that 60 000 is, 2044. Exponential and logarithmic functions for t. the of each exponent. side. Exponential Example A decay casserole is removed from the oven and cools according to the model −0.1t with the equation What a the If b T (t) temperature the 85e , where t is the time in minutes and T is °C. temperature of the casserole when it is removed from oven? the the is = in temperature casserole to of the reach room room is 25 °C, how long will it take for temperature? Answers 0 T (0) a = 85e = The 85 the temperature casserole 0 is of oven, casserole t = is removed from 0 the 85 °C T = 25 25 0 the 1t 85e b When = 25 if the temperature room is Take logarithms of the 25 °C. 5 1t e = = 85 of both sides. 17 5 0 ln 1t e = ln 17 5 0 1t = ln 17 1 .22377... = t The = 12.2 casserole temperature Exercise 1 The (3 will after Solve for t. sf) reach 12.2 room min. T sum of €450 is invested at 3.2% interest, compounded annually . a Write after b 2 In How i b how formula many stages people many after How a for the value of the investment years. early infected a n After the down 2 long years of and a day were days would take value first epidemic the exceed there number rose €600? were by 100 10%. infected ii it the measles each people will for after 250 a week? people to be infected? Chapter 3 Forest fire is area If is 10 how 4 fires left spread to bur n exponentially . unchecked Ever y 15% of hour the that the remaining bur nt. hectares long Joseph will did aircraft are a his it bur nt take until parachute velocity and at the fire 10 000 jump time t for becomes hectares charity . seconds out are his control bur ning? After after of jumping out parachute of the opened –1 was v where m s −0.063t v = 9 + a Sketch b What 29e the was graph of Joseph’s v against speed at t the instant the parachute opened? What c great If d he on his lowest possible speed if he fell from a ver y height? actually landed after 45 seconds what was his speed landing? How e was long when the did it take parachute him to reach half the speed he had opened? b 5 Two variables When of The a n = and x and = 32 n are and connected when n = by 3, x the = formula 108. Find x = the a × n values b American ear thquake 2, x geologist to Charles Richter dened the magnitude of an be I M = log S where M is the ear thquake taken of a 100 (measured km from ‘standard’ 0.001 the by (as the a decimal), amplitude epicenter ear thquake. The of the I of is a the intensity seismograph ear thquake) intensity of a and standard of the reading S is the the Richter Review Evaluate Scale Solve these 3 equations. x−1 = 90 Exponential is b 5 Richter Scale 287 2x+3 a ( S) fur ther . 5 2 mm Severity exercise log in intensity ear thquake millimetres. Explore 1 magnitude 3x = 3 and logarithmic functions 2x c 2 × 3 x = 5 Mild 0–4.3 Moderate 4.3–4.8 Intermediate 4.8–6.2 Severe 6.2–7.3 Catastrophic 7.3+ 3 Solve a b these log + (x equations. + 6) – − log 5 (x = + 2) = c ln d Solve (4x – 7) = ( Solve 2 ) = = 4 The EXAM-STYLE x 5 e log 5 QUESTIONS functions f and g are defined as 2x f (x) = e for all real x ( ) = for x > 0 a State the b Explain ranges why of both f (x) and g (x). functions have inverses. - 1 Find expressions c Find an d Solve for expression the for inverse ( f g)(x) functions f and ( g ° the equation ( f f –1 (x) and g (x). )(x) ° g)(x) = ( g ° f )(x) ° 0.08t 5 The number, where t is a Find b How the n, the the of insects number population long does it obser vations Review of in a days of take after the the colony , is given by obser vation colony after population 50 to n = 4000e commences. days. double from when commenced? exercise ✗ + 1 Solve ⎛ ⎞ = ⎜ ⎝ ⎟ ⎠ + 2 Find the exact Give your value x satisfying the equation + = answer in the where form a, b ∈ ⎛ ⎞ 3 Find the exact value of + − ⎜ ⎝ EXAM-STYLE ⎟ ⎠ QUESTION 4 Write + − as a single logarithm. 5 Solve a c ( − ) = = b + d ( − ) = − + − = EXAM-STYLE 6 If m = log QUESTION 4 and n = log x a log 4 8 8, find expressions in terms of m and n for x b log x 2 c log x 16 d log 32 8 Chapter 3(x−1) 7 The function Describe a f is defined series of for all real values transformations of x whereby by the f (x) = graph e + 2 ≠ 1. of x y = f (x) can EXAM-STYLE be obtained from the graph of y = e QUESTIONS −1 8 Find the inverse function f (x) 2x a f (x) = if 3x 3e f b (x) = 10 f c (x) = log (4x) 2 9 Solve these a b and are simultaneous positive real equations for a and b, given that numbers. 1 log 64 + log a b = 8 log a = ba 2 CHAPTER 4 SUMMARY Exponents Laws of ● ● ● exponents + × = ÷ = = ● ● ● ● = Exponential ● functions An exponential function is a function of the form x f (x) = a where ● The domain ● The range is ● The graph of of a is the the a positive real exponential set of all number function positive real (that is is, a the > set 0) of and all a real numbers. numbers. x the exponential function f (x) = e is a graph −x of exponential growth of exponential decay . and the graph y of f (x) = e is a graph y x f(x) = e –x y = e (0, 1) 1 (0, 1) 0 x 0 x Continued Exponential and logarithmic functions on next page Logarithms Properties of logarithms ● If then ● = ● = ● b ● ● is undefined is for any base a if b is negative undefined = Logarithmic ● To find and an then functions of inverse rearrange a to function make y the ● Generally if switch x and y subject. algebraically , then x y = log y = ln x x is the inverse of y = a a x ● is the inverse of the exponential function y = e x y y = e y = x (0, 1) y = In x x (1, 0) x ● log (a log ) = x and x a a = x a x ln(e lnx ) = x and e = x log (10 Laws x log x ) of = x and (10 ) = x logarithms ● ● ● = − = = ● Change of base formula ● = Chapter Theory of The “The knowledge beauty greatest music, mathematics standing on the has of the mathematics simplicity borderland of all that beautiful Herbert The Beautiful and Have solved you pleased Was it with just solution Look ever at and + it + Turnbull two in correct, stylish, solutions simplify = x² – xy = x² – 2yz = x² – (y² = x² – (y – xz – + + – y – + y² mathematics (x + even to y or + the z)(x was it and all and that is 199 and been because your beautiful? problem: – y – z) z) xy – 2yz science, poetr y (1885–1961) Solution z)(x in supreme ar t.” Mathematicians, (x wonderful of solutions problem was efficient, these Solution a in is inevitableness solution? because was Expand y your simple Westren Great and – y² – yz + xz – yz – z² (x + = (x = x² y + + z)(x (y + – y z))(x – z) – (y + z)) z² + (y + z)² z²) z)² “Pure mathematics is, in its way, the They the both second give us the solution same seems right better. answer It’s and more yet somehow elegant poetr y logical than the first ideas.” and Albert insightful of Einstein one. (1879–1955) Theory of knowledge: The beauty of mathematics Simple, beautiful “The essence equations of mathematics but Stan to Gudder, make is not to model make complicated Professor Here that of are simple things mathematics, some the world things complicated, simple.” University famous of Denver equations 2 Einstein’s Newton’s equation: second E law: = F mc = ma k Boyle’s law: V = p Schrödinger’s equation: Hψ = E ψ m m 1 Newton's law of universal gravitation: F = 2 G 2 r Isn’t it using star tling that These equations moon and inter net human the mathematical bring and universe equations have him helped back, understand can such to put develop the be as described these? man on the wireless workings of the body . These are just five equations – which is your favorite? Is it one possible day that discover mathematics the ultimate and science theor y will of ever ything: A theor y together A theor y outcome carried Now fully known that of has any explains physical predictive experiment and links phenomena? power that for could the be out? wouldn’t ” that all Boyle's that Law be wonderful? explains why bubbles increase in size as they rise to the surface. Chapter Rational CHAPTER functions OBJECTIVES: 1 The 2.5 reciprocal x function x ≠ 0, its graph and self-inverse nature x The rational Ver tical and Applying Before Y ou 1 e.g. x horizontal rational you should Expand function ax + b cx + d and its asymptotes functions to real-life situations start know how to: Skills polynomials. Multiply the graph 1 polynomials check Expand −4(2x a 2 −2(3x − 1) and −2(3x − 1) = −6x 2 2 (x + − polynomials. 5) 6(2x b 2 + 1): 2 − 3) 2 c −x (x + e x (x 3)(x − 7) x d + 2 (x + 3) 8) 3 + 3x (x 3x the Graph 1) = 3x + 3x horizontal 2 Draw these lines x = 0, y = 0, x = 3, x = −2, y = −3, on one graph. y x and ver tical e.g. Graph lines. the = x, x = −1, y y = −2 = −x, = = –x x = 2 4 3 lines 2 y y y = y = x 2, y = 4 x –2 y = 3 and y on the x same = = –2 –1 –4 graph. 3 Recognize and describe 3 Describe y the y 8 a translation. transformations y = 3 x B 6 e.g. Find the translations that map 4 2 that map y = x 3 onto y = onto x functions 2 A and A is B A and B and write 6 x 0 of 2 a horizontal units to the shift down right. of B = x A and equations B –4 2 y the 2 2 Function A B is a units is y ver tical up. is y = Rational (x shift Function 2 B = x + 3. functions − of 2) 3 A –6 –2 A x 0 –4 2 4 6 –8 If you have sounds and quality of a rough 8160 an so the idea MP3 on you recording is minutes player, can that of a you on setting 4GB music. do fit The and MP3 That’s know it? the player how many answer length will songs, depends of hold the 136 on song. hours albums, the However, or approximately 2000 songs of 4 minutes or 1000 songs of 8 minutes or 4000 songs of 2 minutes. This leads us to the function = where s is the number of songs and m is the number of minutes that a song lasts. This function is an example of the reciprocal function, . = In this chapter, reciprocal you will functions use and a GDC other expressed in the form ver tical domain and asymptotes ranges of for . the the explore the functions graphs that can of be + = and to rational Y ou will examine horizontal + graphs of these functions and the functions. Chapter . Reciprocals Investigation Think of pairs E.g. 24 × and add 1, of 12 some – numbers × 2, 8 more × 24 12 8 3 y 1 2 3 8 and your 0 Now ≤ y tr y pairs ≤ the as whose 3, pairs x Show graphing 3 of × product product 8. Copy is pairs 24. the table numbers. coordinates on a graph with 0 ≤ x ≤ 24 24. same idea with negatives, e.g. −12 × −2 End and graph these the Explain what behavior you notice appearance ● the value of x as y gets bigger ● the value of y as x gets bigger as fur ther either the end behavior of of a about graph ● is too. your it is and followed fur ther in direction. graph. Zero does not have 1 ➔ The of reciprocal a number is 1 divided by that number. a reciprocal as is 0 undened. What does For example, the reciprocal of 2 is your GDC show for Taking the reciprocal of a fraction tur ns For example, the reciprocal of is 1 reciprocal A number down. = 1 × . The reciprocal of is or multiplied by its reciprocal 0? ÷ = of ➔ upside ÷ The it 1 4. equals 1. For example 3 × = 1 Geometrical Example in the reciprocal of inverse were 1 Find quantities propor tion describedas 2 reciprocali 2 translation in a1570 of Euclid’ s Answer Elements from = 2 Write as an improper fraction. 2 5 5 2 Check: Reciprocal of = Tur n it upside can find 2 reciprocals of algebraic terms too. The The reciprocal of x is −1 or x is −1 and x × x = 1 5 reciprocal number ➔ 2 × down. 5 Y ou BCE. 5 1 2 300 also or a of a variable called its =1 multiplicative Rational functions inverse. Exercise Find 1 A the reciprocals. 2 a 3 b e the h 3 reciprocals. 6.5 a −1 g Find d f 2 −3 c x b y c 3x d 4y e The + term was f g h Multiply 3 i each quantity by its 6 a b is the reciprocal of the reciprocal of is the reciprocal of the reciprocal of function y b What c Will the when xy x = is happens d Find e What f Will . The ever x The reach when ever 48 the 480 ii value y zero? is third describe 4? x? of y 4800 iii edition reach (1797) two to numbers whose product This the is 1. when x gets 48 000 iv the zero? function of x function used in the Investigation 480 ii value is larger? Explain. 48 i to reciprocal reciprocal use back 24 i to happens x far Encyclopaedia you y as Britannica What the as working. What Find common least c b a your of a For 5 Show at 4 reciprocal. in j reciprocal 4800 iii when y gets 48 000 iv page on 142. larger? Explain. function is k f (x) = x where k Graphs is of a constant. reciprocal functions Investigation Use your GDC to – draw all have graphs all the of graphs in similar reciprocal this Draw a graph of ( x) a 2 = g ( x) b is the effect of Draw a graph of changing ( x) a the value of is the effect of = x the numerator? 2 = g ( x) b 3 = h( x ) c = x x What h( x ) c x 1 2 3 = x What functions investigation. 1 1 shapes. changing the sign of the x numerator? 4 3 Copy a and complete this table for f ( x) = x x 0.25 0.4 0.5 1 2 4 8 10 16 f (x) b What c Draw do the you notice graph of about the the values function. of x and f (x) d Draw f What in the the table? line y = x on the same graph. 4 e Reect f ( x) in = the line y = x do you notice? x 1 g What does this tell you about the inverse function f ? Chapter Asymptotes The on graphs page closer of 143 to the all the functions consist axes but of f (x), two never g(x) and cur ves. actually h(x) The touch in the cur ves or Investigation get cross closer and them. The The axes are asymptotes to the graph. is word derived Greek ➔ If a cur ve gets continually closer to a straight line meets it, the straight line is called = b is an asymptote to the function y = f x → ∞, f (x ) = symbol ‘not together’. f (x) → b y The means (x) y As the an asymptote falling y from asymptotos, but which never asymptote →means = b ‘approaches’. The horizontal line k ➔ The graph of any reciprocal function of the form y has = y a x ver tical asymptote x = 0 and a horizontal asymptote y = b is = The graph of a reciprocal function is called horizontal of the 0 graph ➔ a asymptote of y = f(x). a hyperbola y ● The x-axis is the horizontal x = 0, the y-axis, 6 asymptote. is an k asymptote y = x ● The y-axis is the ver tical 4 y = –x asymptote. 2 ● Both are the all domain the except real and range The reciprocal has many –4 4 6 = 0, the x-axis, in The applications zero. y ● two separate par ts –4 of is an computer graph are reflections = other in y = –6 related y = −x and symmetr y In Chapter 1 you y = for saw x are this that to −x number ● par ticularly x of those each science asymptote. algorithms, y the function x numbers lines of may function. to draw these the inverse function of f theor y. wish to Y ou investigate fur ther . (x), you reflect its graph in the line y = x. If you reflect f (x) = in the line y = x you get the same graph as for f (x). The reciprocal 1 ➔ The reciprocal function is a self-inverse function function, f(x) = , is x one The equation of the function in the Investigation on page 142 of the simplest is examples of a function xy = 24. It can be written as = and is a reciprocal It has a graph Rational simil ar functions to the one shown above. function. that is self-inverse. The design of the Yas Hotel Asymptote Architecture) It a also of the has Formula 1 is in Abu based Dhabi on racetrack (designed mathematical running through by models. the center hotel! Example ✗ For ● each write function: down the equations of the vertical and horizontal asymptotes ● sketch ● state the the graph domain and range. 9 9 a y b = y = + 2 x x Answers a Asymptotes are x = 0 and y = 0 y = 2 y 20 15 10 5 x 0 –6 –4 –2 2 4 6 –5 –10 –15 –20 Domain range b y x ∈ ∈ , , Asymptotes y x ≠ are ≠ 0, 0 x = 0 and The y is 6 f graph the (x) same but of as f (x) the shifted 2 + 2 graph units of in 4 the y-direction. 2 x –30 –20 –10 –2 –4 –6 Domain range y x ∈ ∈ , , y x ≠ ≠ 0, 2 Chapter Exercise 1 Draw B these on separate a graphs. = b = xy c = 8 Y ou need to On the same graph show = do questions 4b and analytically algebra a Sketch the graph of = and write down its the graph of 3b both (using and sketching Sketch c by asymptotes. b able = 3 be and 2 to and using transformations) = + and write down and its using your GDC. asymptotes. 4 Identify and the then horizontal state their and ver tical domain and asymptotes of these functions range. It = b = + 5 The Corr yvreckan, world, the is between coast west The of and heard c = the the roar 16 km of third largest Flood the to draw graphs. islands Scotland. the speed the help − may a of whirlpool Jura tides resulting and and in Scarba inflow maelstrom the off from can the be away . of the surrounding water increases as you approach the center and is modeled by where = s is −1 the speed the center a Use and of in your 0 ≤ s the water in m s and d is the distance from metres. GDC ≤ to sketch the function with 0 ≤ d ≤ 50 200. −1 6 b At c What The what is force distance the (F ) is speed the of required speed the to 10 m s water raise an ? 100 m object from of the mass center? 1500 kg is [ modeled by where = Archimedes believed l is the length of the lever in is to have a place said metres “Give me to stand, and the force is measured in Sketch the graph with ≤ ≤ ≤ How much force would lever enough you need to and I ≤ shall b a newtons. long a and apply if you had a move the earth. ” 2 m N is the symbol for lever? the c How long force of would the lever need to be if you could manage unit a newton. Rational functions i 1000 N ii 2000 N iii 3000 N? of force, the . Rational Have you noticed functions the way the sound of a siren changes as a Sound fire engine or police car passes you? The obser ved frequency frequency measured higher than the emitted frequency during the approach, it at the instant of passing by , and it is lower during the for it moves the obser ved toward you This is frequency called of the sound Doppler when the effect. The source is of per second. equation traveling is: away . her tz number the waves time in is (Hz), identical is is = where −1 ● 330 is ● f the is the speed of obser ved sound in frequency m s in Hz 1 ● f is the emitted ● v is the velocity f is a rational frequency of the source toward you function. 1 h (x) ➔ A rational function is a function of the form since where g and h are this of the course form g(x) px + q and so be zero a value divided polynomials. by In cannot = h(x) we will can be restricted investigate to linear rational zero is undened. functions functions f (x) where + = Example + The −1 A vehicle is coming towards you at 96 km h (60 miles per hour) units must sounds its hor n with a frequency of 8000 Hz. What is the frequency sound you hear if the speed of sound is 330 m s can to −1 −1 = Conver t 96 000 m h metres 96 000 −1 96 000 m h be the equation. same Y ou per hour to round get an numbers approximate answer . second. −1 = = 26.7 m s 3600 Since 330 Observed kilometres per all the ? Answer 96 km h speed of in −1 the of and frequency 1 hour = 3600 seconds f = 330 v 330 × 8000 = 330 = 26.7 8700 Hz (3 sf ) Chapter Investigation – graphing rational functions 1 Use a your GDC to show sketches of y , = y = y x x 1 1 1 = 2 x + 3 2 and y = x Copy b and + 3 complete the table. Rational Ver tical Horizontal Domain function asymptote asymptote Range 1 y = x 1 y = x 2 1 y = x + 3 2 y = x What c the + 3 effect ver tical does changing the denominator d What do you notice about the horizontal e What do you notice about the domain the range the ver tical What f do on asymptotes? and the value of asymptote? you horizontal have asymptote? notice about and the value of the asymptote? k Rational functions of the form y = x − b 1 is A rational function = , where will have that is, a vertical when x = k and b are asymptote consider when the denominator equals zero, b detail horizontal Example in this the Knowledge the The undened. asymptote will be We will 0 constants, end of in more Theor y section the of at chapter . the x-axis. 1 a Identify b State c Sketch the horizontal and ver tical asymptotes of y = x the domain the and function 3 range. with the help of your GDC. Y ou may explore wish the Answers of a The x-axis horizontal x = 3 is ( y = 0) is the asymptote. the ver tical asymptote. Since the numerator will never be 0, the graph touches The of the x = functions never x-axis. is zero 3. { Rational function denominator when this Continued on next page innity. to concept b Domain Range x y c ∈ ∈ , , y x ≠ ≠ 0 3 y 8 6 1 4 y = x – 3 2 x 0 –2 –4 –2 –4 –6 –8 Exercise 1 Identify C the horizontal and ver tical and range. asymptotes of these functions Y ou and state their domain should algebra a = c = + d = = ‘using e = f + = − + g an + h = − Sketch the each domain function and with the help question and = + c your state = + although answers to check with a e − = 1, want b = GDC range. d your may GDC. a of do + you 2 analytic to = + called + method’) is b use (this Use + the = − f = your GDC correct with viewing + window. + g = − h = + 3 When i = lightning instantaneously . strikes, the But sound the + light reaches of the your thunder eyes vir tually travels at −1 approximately the . 331 m s temperature of the However, sound surrounding air. waves The are time affected sound by takes to travel one kilometre is modeled by = where time a b in seconds Sketch If you the are and c graph one the thunder, On the is of the t is temperature for kilometre what the in temperatures away and it temperature is of t is the + degrees from 3 −20 °C seconds the Celsius. to 40 °C. before you surrounding air? hear 4 a same set of axes, sketch y = x + 2 and = Compare linear the two function graphs and its and make reciprocal connections + between the function. b Now do the same for y = x + 1 and = + Chapter Rational functions of the y form ax + b cx + d = ➔ Ever y rational called a function of the form has graph of any rational function has Use your GDC x y = , + x Copy b a ver tical and a + asymptote. Investigation a graph + = horizontal a + hyperbola. The + = y graphing show x + 1 x + = 3 and to – sketches rational y and x complete 2x = the + of 2x , 3 functions y 1 = 3 x + 3 table. Rational Ver tical Horizontal function asymptote asymptote Domain Range x y = x y + 3 x + 1 x + = 3 2x y = + x 2x y 3 1 = x + 3 c What do you notice about the horizontal d What do you notice about the domain asymptotes? and the value of the ver tical asymptote? y ➔ The ver tical asymptote occurs at the x-value that makes the 4 denominator zero. 3 ➔ The horizontal asymptote is the line = a y 2 = c 1 To find the horizontal asymptote rearrange the equation to make x 0 x the –6 subject. –4 –2 –1 ax y + b d = x –2 cx y ( cx cyx + d ) + d = ax − ax = b − dy x = b dy cy The horizontal that is, asymptote when a cy = a or y = c Rational functions –3 + b a occurs when the denominator is zero, = c Example x For the function y + 1 = 2x a sketch b find c state the the ver tical the 4 graph and domain horizontal and asymptotes range. Answers y a 4 3 2 x y + 1 = 2x – 4 1 x 0 –2 –4 –1 –2 –3 b Ver tical asymptote x = 2 When 2x a c − 4 = 0, 1 Horizontal asymptote y x ∈ , x ≠ = 2 a = = 1, = y = 2, 2 Domain c x c 2 1 Range y ∈ , y ≠ 2 Exercise 1 Identify and the then a D state the Match b = b i − y c x 1 x 3 d = ii 8 6 4 2 2 x –6 y 4 –4 + = 6 –2 = graph. + y –2 functions d 8 –4 these + = − = − the of range. c with a and asymptotes + function ver tical = the and domain + = 2 horizontal 0 –4 x –2 –2 –4 –6 Chapter y iii y iv 8 8 6 6 4 4 2 2 x 0 x 0 –2 –4 –2 –2 –2 –4 –6 3 Sketch and each using your GDC and state the domain range. a function + = b c + = + − + = + + Check d = e = f by using graph g = 4 Write x 5 = a −4 Chris and a design and in has T-shir ts ver tical at y = surfers It that will it to function. asymptote at 3 and cost will the GDC = a for garage. estimate − asymptote their they that answer your set up $450 cost a to $5.50 T-shir t set to up the print T-shir t. Write a Write linear a T-shir t c horizontal Lee T-shir ts. b function business equipment a i − rational = and printing each h your = What rational of is function Remember to domain x giving take function producing the C (x) of of the A (x) the total cost of cost into account. set-up giving the average producing x cost per them. A (x) in the context of the problem? Explain. d Write e Find down the ver tical asymptote of A (x). Sketch this the value Exam-Style 6 horizontal have rule is over age of ‘Take plus the 12. the context for of A(x). the What meaning does problem? Question Y oung’s the in asymptote age a way two, of the Multiply of calculating based child this on in the adult years number by doses and the of medicine for children dose. divide adult by their age dose.’ This is modeled by the function where = dose, a is the adult years. Rational functions dose in mg and t c is the child’s + is the age of the child in the function. a Make of a table of values for ages 2 to draw to 12 with an adult dose 100 mg. b Use your c Use the values from a a graph of the function. graph to estimate the dose for a 7 -year old. d Write down e What does Y oung’s 7 The a new cost for cost a a Sketch a d Since e Explain the A it of the the horizontal horizontal asymptote. asymptote mean for electricity costs and function as a per $550. that lasts year for a refrigerator Determine for 15 the years. total is $92. annual Assume costs electricity . that gives function of the the annual number cost of of a years you own refrigerator. graph window? f of refrigerator refrigerator c of purchase Develop the value refrigerator include b the equation r ule? average A the of Label this is a the that the function. What is an appropriate scale. rational meaning function, of the determine horizontal its asymptotes. asymptote in terms of refrigerator. company will last difference Review offers at in least a refrigerator twenty years. that Is costs this $1200, but refrigerator says wor th that the cost? exercise ✗ Extension material Worksheet 5 fractions Exam-Style 1 Match the function with the ii CD: aysmptotes graph. v a iii = iv and on Continued Question i - + = vi + + y b y 8 6 6 4 4 2 2 0 x –2 –2 0 x –2 –2 –4 –4 –6 –6 Chapter Exam-Style QuestionS c d y y 6 8 4 6 2 4 x –2 x 0 –1 –3 3 –4 –2 –6 –4 e y f y 6 6 4 4 2 2 x 0 –2 x 0 –2 –4 –4 –6 –6 2 Given a b 3 i Sketch ii Determine iii Find For the each domain the of and = = c + = + function. the ver tical domain these and and range functions, horizontal of write the asymptotes of the function. function. down the asymptotes, range. a b y y 6 8 5 4 f (x) 6 = 6 x + 4 f (x) = – 3 4 x 2 x 0 –6 –2 –4 –2 x 0 –6 –4 –2 –4 –2 –6 –4 –8 –6 –8 y c y d 6 8 4 6 2 4 –3 f (x) 2 f (x) = – x + = + x – 5 1 2 6 2 0 x x 0 –8 Rational functions –6 –4 4 –4 –2 –6 –4 –8 –6 6 8 4 A group of weekend a If c the in want a spa. health number terms b Draw c Explain The students represents this 5 at a of f is given student an = , x ∈ , x Find the ver tical iii Write b Find c Hence down the sketch the to represents show the cost and domain of −2 asymptote asymptote the of y = f (x) graph. the point P at which the of the intersection graph of y = of f the (x), graph with showing the the axes. asymptotes lines. with the help of your − State the b = + c = + − e London to f from = flies of GDC. range. = distance of = airline graph intersect. function and the Question each of of coordinates An and s equation range 2 a exercise Exam-Style domain the points dotted Review for students. on ≠ ii d voucher + horizontal a $300. by the a teacher costs Find Sketch each write of their voucher function. limitations asymptotes 1 the i by for number of give function. a cost students, the any function (x) of graph f the to The New = + Y ork, which is − a 5600 km. a Show that this information can be written as = −1 where and b is Sketch and c t s If of 0 the the the a ≤ the is t average time graph ≤ in of speed of the plane in km h hours. this function with 0 ≤ s ≤ 1200 20. flight takes 10 hours, what is the average speed plane? Chapter Exam-Style 3 People with amount of Questions sensitive time skin spent in must direct be careful sunlight. about The the relation + = where the is the spend a Sketch b Find s i in = relation number what mayor Bangkok. of s this is The the = and that ≤ minutes 40 cost in population s the sun person skin with = value, sensitive gives skin damage. ≤ skin scale can ≤ be ≤ exposed when 100 asymptote? out (c) is a that iii represents giving s without when of horizontal the time sunlight is Explain percent direct of ii d city minutes 10 What The in amount this the c in time maximum can 4 m for face Thai is a person masks baht given with during for giving a sensitive flu skin. outbreak masks to m by = a Choose the b the 20% of the The suitable scale and use your GDC to help sketch cost of supplying 50% ii iii 90% population. Would this 5 a function. Find i c it be model? function f possible Explain (x) is to supply your defined all of the population using answer. as f (x) = , + a Sketch b Using your the equation the value Rational value functions of sketch, ii the ≠ cur ve i iii the x of of of the the f for write each −3 ≤ x ≤ 5, down asymptote x-intercept y-intercept. showing the asymptotes. CHAPTER 5 SUMMARY Reciprocals ● The ● A of reciprocal number a number multiplied by its is 1 divided reciprocal by that equals number. 1. For example 3 × = 1 −1 ● The of reciprocal x is or −1 x and x × x =1 The ● If reciprocal a cur ve never ● The gets meets graph continually it, of function the any closer straight line reciprocal is to a straight called function line but an asymptote of the form y = has a ver tical asymptote x = 0 and a horizontal asymptote ● The graph y = of 0 a reciprocal function is called y a hyperbola x = 0, the y-axis, 6 ■ The x-axis is the horizontal ■ The y-axis is the ver tical ■ Both the domain and asymptote. is an 4 asymptote. range are all asymptote y the real = –x 2 numbers f except zero. x –2 –4 ■ The two separate par ts of the graph are 4 y of each other in y = = y ● y The = x and y = reciprocal Rational −x are lines function is 0, the x –4 −x is ■ 6 reflections a of symmetr y self-inverse for this = an asymptote. x –6 function. function functions ● A rational function is a function of the form = y where g and h are polynomials. 4 ● Ever y rational function of the form has called a + = a graph 3 + hyperbola. a y ● 2 = c The the ver tical asymptote denominator occurs at the x-value that makes 1 zero. x –6 ● The horizontal asymptote is the line –4 –2 = –1 d x –2 = c –3 Chapter Theory of knowledge Number Egyptian systems fractions 3 The ancient Egyptians only 1 In algebra: = 4x fractions with a numerator of for 1 example: , 3 etc. meant that each algebraic Egyptian expression as fraction. 4 instead of they 4 5 7 23 3x 4x 4x 24x wrote 4 1 Write an 3 This 4x 1 , 2 + 2x 1, 1 1 used 1 + . 2 Their fractions were all in the 4 Where 1 and form are called uni t do you think this could be fractions . n useful? 2 Numbers such as were represented as 7 What 2 sums of unit fractions (e.g. 1 = 7 the twice (so same fraction + 4 could not 1 of these ). be it possible to write ever y fraction used an Egyptian fraction? 1 = 7 limitations 28 as 2 the fractions? Is Also, are 1 + 7 was not allowed). How 7 5 1 do you 1 know? For example, would be 8 Write these + 2 as unit 8 fractions. 5 5 2 6 6 8 5 7 In an Inca quipu, the strings represent numbers The Rhind 1650 BCE fractions 200 Theory of knowledge: Number systems Mathematical contains copied years older! a from Papyr us table of another dated Eg yptian papyrus Is there a dierence between 25¢ zero More had the and than 2000 systems ninth for a a circle this became Who What Make Notice Now We rst some How par t did on the zero before of in keep The Hindu a the name place rows’. sifr that of The if, tens, Arabs eventually was nothing? the subsets and the 1 be is {0} were What not something. the tentative Mayan and equation BCE. and {0, 1, 2, another 9 3}. is { x = 3² about a year sure + what Zeno’ s use Inca of of to }. and do the equation 3x = 0. zero? with paradoxes (a zero good and they topic to questioned research) how depend in zero. cultures understand In and remarked the cultures number. that? subset Greeks could appears ‘to of mathematician al-Khwarizmi (empty). Solve CE ancient nothing 1 Islamic used that all one this. have The of be and absence zero? used that tr y the an zero. mean list Babylonian number sifr used was a no word this CE, should circle our Does ago, Muhammad calculation, little called years representing centur y philosopher in nothing? zero? ative? What happens if you divide zero by anything? g pens The Mayans shell symbol represent if used you divide zero by by zero? zero? a to zero. Chapter Patterns, sequences and series CHAPTER OBJECTIVES: Arithmetic 1.1 geometric series. sequences and sequences Sigma and series; series; sum sum of of nite arithmetic nite and series; innite geometric notation. Applications n The 1.3 binomial theorem: expansion of ( a + b ) , n ∈ ; ⎛ n ⎞ Calculation of binomial coefcients using Pascal’ striangle and ⎜ ⎝ Before Y ou 1 you should Solve change e.g. the Solve and how to: quadratic subject the ⎠ start know linear ⎟ r of a equation Skills equations and 1 formula. n(n – 4) = 12 check Solve each a 3x b p(2 c 2 2 – 5 – equation. = p) 5x = + 7 –15 n n – 4n = 12 4n – 12 = 0 2) = 0 + 9 = 41 2 – n 2 (n – 6)(n n e.g. –2, Make ac b 2 = + = = b ac n b – = the for a 6m b 2pk + k 8k = 30 6 subject of this 3 If T 3 Substitute known e.g. the values into – 5 = 3 formula. 3 + Solve T = 2x (x + 3y), then find the value of when a x = 3 and b x = 4.7 y = 5 y = formulae. and –2 4 Using formula A = of = 2 3p – 10q, x find the value A if p 4 A = 3p – – = 3(2) A = 3(16) A = 48 10(1.5) – q = 1.5 4 Using value 10q 4 A and 15 the of formula m m if a x = 5 and y = 3 b x = 3 and y = –2 c x = –5 A = – 15 sequences = 33 Patterns, and and series = 2 3 – y , find the The bacteria in this petri dish are growing and reproducing; in this [ Bacteria petri case the total measured mass The at as mass of patter n after 8 this help will the make we you predict ● work ● predict ● calculate the ● calculate how in be use or how the to 24 a total it will will dish the so At 10:00 8 a.m. will be the 6 mass grams, a is the on. forms the a numerical mass of patter n. bacteria in the dish near patter ns. and distant Patter ns future. can For to: countr y take natural it and at mathematical a distance long hours. mass predict about of two in hours. patter ns long long in study population how total grams, used will ever y the predictions ● out 12 hours can the so bacteria 12 chapter example, be could hours, us doubles 3 grams, 12:00 This In mass growing dish to pay resource that take in a for 20 off will years a loan last bouncing an bank ball will investment to travel double value. Chapter . Patterns Investigation Joel He decides saves week, and Copy a and to $20 so and how star t the and – saving saving rst sequences money money. week, $25 the second week, $30 the third on. complete much he the has table below saved in to total, show for Week Weekly T otal number savings savings 1 20 20 2 25 45 3 30 75 how the much rst 8 Joel saves each week, weeks. 4 5 6 7 8 b How much will c How much money d How long T ry e Let let Let of In the week as T write the for for total 10th save him week his the to the amount formula represent investigation a form number are some 8, 11, 14, 400, 1, 4, 9, in week? total save a amount of in the total of money In of the rst at money he 17th year? least Joel saves week? $1000? saves each each week, week. and number . the total savings, 5, 10, 15, amount and Patterns, The total is a let n of money represent Joel the has saved. number 25, 100, 25, … … sequences amounts to a sequences. … and series of money of Joel money saves he has each saved sequence. patter n … 200, amounts according number 20, the different sequence 17, 16, a order Here 800, above, sequence. passes par ticular a the in Joel for formula represent to will take represent form A a it save weeks. time ➔ write M n T ry f to will Joel of numbers r ule. arranged in a ➔ Each individual called In is the 11, Y ou a can or element, of a sequence is term sequence the number, third also 8, 11, term use is the 14, 17, …, 14, and notation so u the first term is 8, the second term on. to denote the nth term of a n sequence, So u for = where 8, 11, 8, u 1 Y ou n is 14, = a positive 17, 11, … u 2 can you = 14, integer. could and say so on. 3 continue the patter n if you notice that the value previous term: of each Sometimes, term is three greater than the value of the letters 8, 11, 14, 17, 20, 23, represent 26 a For this sequence, you could write: = u 8 and u 1 This is called a recursive formula, in = u n+1 which the + a example, a , t n on the value of the previous , of the sequence one-half the 800, value 400, of the 200, 100, previous terms of or we x might n to n term. represent In to term use depends the u sequence. For of use than 3 n value we other …, the value of each term a the nth term sequence. is term. In this case, = u 800 and = + 1 Example Write a recursive a 9, 15, b 2, 6, 21, 18, 27, 54, formula for the n th term of each sequence. … … Answers u a = 9 and u 1 = u n+1 + 6 To get add u b = 2 and u 1 from one ter m to the next, you from one ter m to the next, you n = 3u n+1 To 6. get n multiply by 3. Sometimes Sometimes term of of a In the a term it is more sequence. without useful With having a to write general to know a general formula for the formula, the value you of can the find the previous nth value called rule the for 1, 4, 9, 16, 25, … , each term is a perfect 2 first term is term’. that n, square. term number , will 2 , 1 nth term. the The is ‘general the Remember sequence this the second is 2 , and so on. A general formula always be a whole 2 for the nth term of this sequence is u = n number . n In the sequence 5, 10, 15, 20, 25, … , each term is a multiple of We could not 3 5. have a ‘ th’ term, or a 4 The first term is 5 × 1, the second is 5 × 2, and so on. ‘7.5th’ A general formula for the nth term of this sequence is u = term. 5n. n Chapter Example Write a 4, a general 8, 1 12, 1 , , 6 for the n th term of each sequence. … 1 , 3 formula 16, 1 , b 9 … 12 Answers a u = 4n Each ter m is a multiple of 4. n 1 b u = The denominators are the multiples n 3n of Exercise 1 Write down 3, 7, 11, c 3, 4, 6, u a 15, … , … down 10 the and and first = ( = a 2, c 64, Write 1, 2, 4, d 5, –10, 8, … 20, –40, … 6.0, 6.01, 6.012, 6.0123, … terms in ) each u b sequence. = 3 and = + 1 + ) u d = x and 1 recursive 4, b ( 4 four + a sequence. = Write each f + 1 3 in u terms … 1 c three = next 13, Write the 9, 2 A a e 3. 6, 32, 8, for each … 16, down formula sequence. 1, b 8, the … 7, d first four terms in 3, 9, 12, each 27, 17, … 22, … sequence. T o nd the rst term n a u c u = 3 = 2 u b n 6 a a 2, c 64, The n = 1; to n u d general 4, 6, 32, 2 , 2 3 = n nd the second use n 2 term n Write 1 + substitute 1 n e −6n n n 5 = 8, the nth 8, … term of 9, each b 1, 3, 27, d 7, 12, f x, 2x, is known 17, = and so on. sequence. … 22, … 4 , , 3 for … 16, 3 , formula 4 … 3x, 4x, … 5 sequence 1, 1, 2, 3, 5, 8, 13, … as the Fibonacci sequence. a Find b Write . the a 15th term recursive Arithmetic of the formula Fibonacci for the sequence. Fibonacci sequence. sequences [ Fibonacci, as In the sequence 8, 11, 14, 17, …, the value of each term is than example of Patterns, the value of the previous an ari thmetic sequence , sequences and series term. or This sequence arithmetic of known Pisa three (Italian greater also Leonardo is an progression. c. 1175 – c. 1250) ➔ In an arithmetic sequence, the terms increase or decrease by a Examples of arithmetic progressions constant value. This value is called on or d. The common difference can appear the common dierence , be a positive or a the Ahmes negative Papyrus, which dates value. from For 8, about 1650 BCE. example: 11, 14, 17, … In this sequence, u = 8 and d = 3 = 35 and d = –5 = 4 and d = 0.1 = c and d = c 1 35, 30, 25, 20, … In this sequence, u 1 4, 4.1, 4.2, 4.3, … In this sequence, u 1 c, 2c, 3c, 4c, … In this sequence, u 1 For any arithmetic sequence, u = u n+1 We can find difference, In an d, to term the arithmetic = u any the first of the + sequence previous d n by adding the common term. sequence: term 1 u = u 2 u = u 3 u d + d = (u 2 = + d = = d) + d = u + + 2d) + d = u 1 u + d = + 3d + 4d 1 (u 4 2d 1 (u 3 5 + 1 u 4 u + 1 + 3d) + d = u 1 1 … … = u u n ➔ + (n – 1)d 1 Y ou can find formula: Example u the = u nth + n 1 12th term term (n – of an arithmetic sequence using the 1) d a Find the b Find an of expression the for arithmetic the n th sequence 13, 19, 25, … term. Answers a u = 13 and d = 6 Find these values by looking at the 1 u = 13 + (12 = 13 + 66 = 79 – 1)6 sequence. 12 u For n = the 12 12th into ter m, the substitute for mula 12 u = u n b u = 13 + (n – 1)6 + (n – 1) d 1 For the nth ter m, substitute the n = 13 + 6n – 6 values of u and d into the for mula 1 u = n 6n + 7 u n = u + (n – 1) d 1 Chapter Example If Find the number of terms in the arithmetic a sequence sequence continues 84, 81, 78, …, and there term, Answer u = 84 and = 84 + d indenitely 12. = –3 Find these values by looking at it is is no an nal innite sequence. the 1 u (n – 1)(–3) = 12 If sequence. a sequence ends, or n Substitute the values of u has and d into a ‘last term’ it 1 the formula u = u n 84 – 3n There + 3 = 87 3n = 75 n = 25 are 25 – 3n terms in = 12 Solve for a + (n – 1)d 1 n. the sequence. Exercise For 1 each sequence: i Find the ii Find an a 3, c 36, e 5.6, Find 2 B 5, a the an 9, the nth … 6.8, …, term. 25, b 46, 6.2, 15, for … 41, … of terms in d 100, f x, each 255 x 55, 87, + a, … 74, … x 2a, + … sequence. b 4.8, d 250, 5m, 8m, …, 80m f x, 5.0, 5.2, …, 38.4 221, 192, …, –156 3x + 3, 5x + 6, …, 19x + arithmetic common sequence, u = 48 and u = 75. Find the first term and 12 difference. Answer u + 3d = u + 3d = 75 the 3d = 27 to d = 9 times. 9 48 To get from the 9th ter m, 12 u , to 9 12th ter m, u , you would need 12 u = 9 u + (9 – 1)9 u + 72 u 48 To = 48 for mula. = –24 1 first –24, term and difference the = 1 is add find Patterns, of the is the sequence common 9. sequences and series common the 1 The 27 9 the 40, Example In expression 2m, e term. number 10, c 6, 15th first dif ference ter m, use the 3 nite sequence. is Exercise An 1 C arithmetic Find the common EXAM-STYLE In 2 an sequence has first term 19 arithmetic sequence, the common 3 Find the value of x 4 Find the value of m u = term. or sequence This In a 2, The For in the 37 and u in the = 4. 21 and the arithmetic first term. sequence arithmetic 3, sequence x, m, 8, … 13, 3m – 6, … sequences 18, is 54, an …, each example sequence , geometric called 31.6. term of is three times the previous a geometric sequence , progression. multiplying is 6, sequence geometric ➔ difference Geometric the term QUESTION Find In 15th difference. 10 . and the the common previous r, term ratio , common ratio, each can be term by or a can be constant obtained value. by This value r positive or negative. example: 1, 5, 25, 125, … u = 1 and r = 5 = 3 and r = –2 = 81 1 3, –6, 12, –24, … u 1 81, 27, 9, 3, … u and = 1 2 k, k 3 , k 4 , k , … u = k and r = k 1 For any geometric sequence, u = (u n+1 sequence For any u by multiplying geometric = the = u = u first the )r. Y ou can find any term of the n previous term by the common ratio, r. sequence: term 1 u 2 × r × r 1 2 u 3 = (u 2 × r) × r = u 1 × r 1 2 u = u 4 × r = (u 3 × r 3 ) × r = 1 u × r × r 1 3 u = u 5 × r = (u 4 × r 4 ) × r = 1 u 1 … … n = u u n ➔ Y ou × – 1 r 1 can find the nth n formula: u n = u (r – term of a geometric sequence using the 1 ) 1 Chapter Example Find the 9th term of the sequence 1, 4, 16, 64, … Answer u = 1 and r = 4 Find these values by looking at the = 9 1 sequence. 9 u – 1 8 = 1(4 ) = = 1(65 536) = 65 536 1(4 ) For the 9th term, substitute n 9 n into the for mula u = u n u – (r 1 ) 1 9 Example Find the 12th term of the sequence 7, –14, 28, –56, … Answer u = 7 and r = 7((–2) = –2 Find these values by looking at the 1 sequence. 12 u – 1 11 ) = 7((–2) For ) the 12th ter m, substitute 12 = 7(–2048) n = –14 336 u = 12 into n u Exercise For each 16, c 1, 10, e 2, 6x, 8, sequence, 4, find the Example a … 100, 18x for mula ) b … d – 4, 25, 12, … f a –36, 10, 7 , 4, 6 b, a ratio 7th term. … 5 , the … 2 b and a 3 b , … geometric sequence, u = 864 and u 1 the the 1 1 common 2 Find – (r D a In u n 12 1 = common = 256 4 ratio. Answer 4 u = u 4 – 1 (r 3 ) = 1 u (r ) Substitute = 864(r and u ) = 256 4 n u 256 = u n 8 – (r 1 = = 864 27 8 r = 3 Solve 27 2 r = 3 Patterns, sequences and series for 1 ) 3 r = 4, u = 864, 1 3 256 n 1 r. into the for mula Example For the that geometric the nth term sequence is greater 5, 15, than 45, ... find the least value of n such 50 000. Answer u = 5 and r = 3 1 Find n u = 5 × – u 1 and r by looking at the 1 3 n sequence. Substitute u = 5 and r = 3 into the 1 n for mula u = u n You can of n. for into 1 ) 1 use value – (r the GDC First, to enter help the find the for mula GDC u a function. Let help x represent n, as shown. Plus and GDCs look values The n = 10, since u > of 9th ter m CD: demonstrations variable Now on is at the TABLE the first ter m is n Alternative the n to see Casio are on for the TI-84 FX-9860GII the CD. the ter ms. 32 805, and the 10th 98 415. 50 000 10 Exercise 1 A geometric Find 2 A For that 4 the the each the a 16, c 112, A sequence first geometric Find 3 E and term and geometric nth 24, term 36, –168, that find and sequence first geometric Show term the has the 252, greater ... sequence two 2nd are has two term common 3rd term find than 5th term 3.2. and 6th term 144. ratio. least value of n such 1000. 1, d 50, 2.4, values 5.76, 55, term possible possible and ratio. the b first 50 –18 common sequence, … there the is has 9 60.5, and values for the … ... third for the second term 144. common ratio, term. Chapter Find 5 the value EXAM-STYLE Find 6 7x . – the 2, u , the u 1 , + 4, + , u 1 u (Σ) + sequence 18, p, 40.5, … , u ways of …, of x in the geometric sequence … at a u to add sequence is a and the series terms gives of a sequence. a series sequence. n + u 3 Greek geometric notation 4 2 the value 3x, looks 3 in QUESTION terms u 2 u The 4x section Adding p positive Sigma This of … + + u 4 letter is a series. n Σ, called ‘sigma’, is often used to represent sums of values. When ➔ ∑ means the sum of the first n terms of a sequence. sum of Y ou read this ‘the sum of all the terms u from i = 1 to i = n’. i arithmetic common sequence difference sequence is = u 6n 6. + 8, A 14, 20, general … r ule has for first term the nth 8 term and of this ( + 2 n The sum of the first five terms of this sequence ∑ is This To to means ‘the calculate 5 into sum this the of sum, all the terms substitute expression 6n + 2, all and 6n the + 2 from integer add ) = n = 1 values to of n n = 5’. from them: ( ∑ + ) = [6(1) + 2] + [6(2) + 2] + 32 + [6(3) + 2] + [6(4) + 2] = + = Example 8 [6(5) + 14 + + 2] 20 + 26 = 100 4 2 a Write the expression ∑ ( x b Calculate the sum of x 3 ) as a sum of terms. = 1 these terms. Answers 4 2 a ∑ ( x x 3 ) = 1 2 = (1 2 – 3) + (2 – 2 + = b represent values in (3 –2 –2 + + 1 Patterns, 3) Substitute consecutive integers 2 – 1 + 3) + 6 + 6 + (4 + – 3) beginning 13 13 = sequences with 18 and series x = with 4 x = 1 and ending 1 you sigma are a this = form, The you using notation Example 8 a Evaluate the 2 ∑ ( expression a = ) 3 ‘Evaluate’ Answer 8 Substitute a 3 2 ∑ ( a = ) = 4 2 + 5 2 + 6 2 + consecutive nd integers the tells value you so to the 7 2 + 2 beginning with a = 3 and nal ending answer will be a 8 3 + 2 with = 8 + + = the 128 + + 32 + a = 8 64 256 504 Example Write 16 number . series 3 + 15 + 75 + 375 + 1875 + 9375 using sigma notation. Answer n u = – The 1 3(5 ter ms are a geometric ) n progression, common with ratio first ter m 3 and 5. 6 This n ∑ ( 3 series six ter ms of the Write F an expression a 1 + 2 b 9 + 16 c 27 d 240 e 5x f 4 + 7 + 10 g 1 + 3 + 9 + + 25 + + 3 + + + + h a + Write 2a + 7x + + + + 23 120 6x 4 25 2 2 first progression. = 1 Exercise 1 the )) geometric n is 1 (5 5 + + each + 21 60 + + 6 + + + … + series + + + + + a + using sigma 8 17 + 7.5 10x 55 59 049 5a sum of terms. 8 7 5 11 r a a n 3n 1 b notation. 5 4a as series 15 4 + 7 19 9x … + each 49 30 8x 13 27 3a + 36 3 + for 4 c ∑ ( 5 ( 2 n ) d x Remember , a 1 r = n 3 nd Evaluate. 7 5 9 n 1 8n 5 b 3 r 1 the need 10 to tells you value, give so to you numerical 2 r a word 5 evaluate 3 the 1 c m m 1 d x 7 x 4 answers. 4 Chapter . Arithmetic series Carl Friedrich Gauss (1777–1885) The sum of the terms of a sequence is called a series. The sum arithmetic sequence is called an ari thmetic series said the terms of an is to be the greatest mathematician For so example, 5 + 12 + 5, 19 12, + 19, 26 + 26, 33 33, + 40 40 is is an an arithmetic arithmetic sequence, 19th how series. the When a series has only a few elements, adding the individual it not a difficult would helpful be to find denotes S task. ver y a the However, if a time-consuming r ule, sum or of formula, the first n series to add for has all 50 evaluating terms of a terms these or terms. 100 It sum series. For a of of the F ind out worked the out rst terms integers. terms will arithmetic centur y. Gauss 100 is often of be series. series n Remember with n must S = u n For S u + = 2 u + + u 3 (u 1 we u arithmetic n If + 1 an + 4 d ) + this (u 1 reverse … + + n order of would be the same, positive 2d ) + be: (u 1 the a n would + be integer . u 5 series + u + 3d ) + (u 1 the terms + 4d ) + … + (u 1 in the + (n – 1)d) 1 equation, the value of the Star t sum that terms, and it would look like with the nal this: term u , then the next- n S = u n + (u n – d ) + (u n – 2d ) + (u n – 3d ) + (u n – 4d ) + … + n u to-last 1 term is u n and Adding these two equations for S ver tically , term by so term, n 2S = (u n This is + (u = ) + (u u ) + u 1 added ) + (u n n + u 1 times, ) + (u n + 1 u ) n + (u 1 + u ) n so: n n(u n + u 1 Dividing + n 1 2S u 1 ) n both sides by 2 gives: = ( + + ) Substitute ( − ) for u , then n = ( + + ( − ) ) Y ou find using the the sum of the first = + ) or Patterns, sequences = ( terms of an ( n formula: ( − ) ) can series + ➔ ( = and series + ( − ) ) arithmetic + … + (u 1 + u n ) on. – d, Example Calculate 29 + 21 the + 13 sum + of the first 15 terms of the series … Answer u = 29 and d = –8 1 15 S = ( 2 ( 29 ) 15 + (15 − 1) 8) ( For ) the sum of 15 ter ms, 2 substitute = 7.5(58 = –405 – 112) n = 15 into the for mula n S = 2u ( n + (n 1 − 1 d ) ) 2 Example a b Find the 14 15.5 + Find the number + 17 sum of + of terms 18.5 the + in … the + series 50 terms. Answers a u = 14 and d = 1.5 Find these values by looking 1 at u = 50 the To sequence. find n, substitute the n u = 14 + (n – 1)(1.5) = 12.5 + 1.5n values you know into the n 12.5 + 1.5n = 50 1.5n = for mula 37.5 u = u n n = 25 + (n – 1)d 1 Solve for n. 25 b S = (14 25 + 50 ) Substitute 2 the = 12.5(64) = 800 of last n the ter m into the first and ter m, the value for mula n S = (u n + u 1 n ) 2 Exercise 1 Find 3 2 + 2.6 3 Find – 3 + 94 the 3.4 sum + of + the first 12 terms of the arithmetic series the first 18 terms of the arithmetic series first 27 terms of the arithmetic series first 16 terms of the series (3 ... of 88 sum + of ... sum + the 5x) sum 9 the + Find (2 + + 100 4 the 6 Find G + of – the ... the 4x) + (4 – 3x) + ... Chapter EXAM-STYLE 5 6 Consider QUESTION the a Find the b Find the Find the Write 120 number sum sum Example a series of of of + terms the the 116 + in 112 the ... + + 28. series terms. series 15 + for the 22 + 29 + … + 176 an expression S , sum of the first n terms, of the series n 64 b + 60 Hence, + 56 find + … the value of n for which S = 0 n Answers a u = 64 and d = –4 Substitute the values for 1 u n S = d into the for mula 1 ( 2 ( 64 ) n and + ( n − 1) ( −4 ) ) n S 2 = ( n 2u 1 + (n − 1)d ) 2 n = (128 − 4 n + 4 ) 2 n = (132 − 4 n ) 2 2 S = 66 n − 2 n n Set 2 b 66n − 2n = S 0 = 2n(33 – n) = can = 0 or n = two = 33 your the positive 1 An series has u = 4 and S 1 the value EXAM-STYLE 2 a n. The equation the GDC.) the When equation we solve usually by has to word hence question use your answer in number integer, of we ter ms must disregard n be = a 0 Write of the = 1425 30 common difference. QUESTION an expression for S , for the series 1 + 7 + 13 + … n b Hence, find the value of n for which S = 833 n 3 a Write an expression for S , for an arithmetic series n with u = –30 and d = 3.5 1 b Hence, find the value of n for which S = 105 n 4 In Januar y they sell 2012, 600 a How b Calculate Patterns, a new drinks, many then drinks the total sequences coffee and will 700 shop in they number series sells March, expect of and to drinks 500 sell they drinks. so in on In in Febr uar y , an arithmetic December expect to sell 2012? in 2012. progression. in tells you previous this H arithmetic Find for this solutions. Since Exercise solve solve 33 factoring, n and also 0 using n 0, n (You par t. 5 In an and the 6 In arithmetic the of common an ten sum the first the ten 2nd terms term is is –20. four Find times the the first 5th term term, and difference. arithmetic times find sequence, the the series, sum common of the the sum first difference 3 of the terms. and the first If 12 the value terms first of is term equal is to 5, S 20 . Just Geometric as an arithmetic sequence, a a the following series geometric geometric Adding series is the is series sum the of the sum of terms the of an terms arithmetic of sequence. terms of a geometric sequence gives the equation: Multiply this 2 = S u n + u 1 r + u 1 + = u n r + u 1 u r + + + u u 1 4 r + u 1 – 2 n r + u 1 3 r n … 1 2 rS 3 r 1 r … + n – S n = – u n + u 1 r by of r 1 r u –1 n r + u 1 Subtract r the rst 1 equation rS sides 1 n + 1 – both equation from the both sides n = u 1 r – u 1 second. 1 n S (r – 1) = u n (r – 1) 1 Factorize of ( the ) equation. = Y ou ➔ Y ou can find the sum of the first n terms of a geometric may nd convenient using the more to use the formula: rst it series formula when ( ) or = r , where r ≠ > 1, as it avoids 1 using a negative denominator Example Calculate the sum of the first 12 terms of the series 1 + 3 + 9 + ... Answer u = 1 and r = 3 Substitute the values of 1 12 1 (3 S 1 ) u , r and n into the for mula 1 = 12 n 3 1 u 1 S (r 1 ) = n 531 440 r 1 = 2 = 265 720 Chapter Example Geometric a Find the 8192 b + number 6144 Calculate + the of terms 4608 sum … + of the in + the series series are often the study seen in 1458. of fractals, terms. such as the Koch snowake. Answers 6144 a u = 8192 r and 3 = = Find r by dividing u 1 n 3 ⎛ 1 Substitute the values ⎠ n the for mula u = u n n 729 3 ⎛ = 1 ⎟ 4 ⎝ ⎠ 6 3 ⎛ = 3 6 3 6 729 = 729 and 4 = 4096 ⎞ = ⎜ 6 4096 4 ⎝ ⎟ 4 You could = also solve this equation ⎠ using logarithms 6 (see = Example 19). 7 Substitute 7 ⎛ ⎛ 8192 ⎜ 1 3 ⎜ ⎜ ⎝ values of u , r 1 ⎟ ⎟ 4 the ⎞ ⎞ and n into the for mula ⎟ ⎠ ⎝ S into ) 1 6 n know 1 ⎞ ⎜ 4096 1 – (r = 8192 – you ⎟ 4 ⎝ 1458 1 ⎞ ⎜ b u 4 1458 = 8192 n by 2 8192 ⎠ n = u 7 1 3 S 1 (r r 4 ) 1 [ You ⎛ 14 197 ⎞ 8192 1 = n ⎜ can also calculate sums Koch snowake using ⎟ 16 384 ⎝ the seq (and sum) functions on ⎠ = 1 your GDC. 4 = 28 394 Exercise 1 I Calculate the value of S for each geometric series. 12 a c 2 0.5 64 + – 1.5 32 Calculate + + 4.5 16 the – + 8 value … 0.3 b … + d of S for ( each + 0.6 + ) + + 1.2 ( + + ) … + ( + ) + series. 20 0.25 a + 0.75 + 2.25 … + b + + + … c 3 – 6 + 12 EXAM-STYLE – 24 + … d + ( ) + ( ) + ( ) + QUESTION So 3 For each geometric at i find the number ii calculate far we of arithmetic 1024 b 2.7 + 1536 10.8 + 2304 43.2 + + 590.49 Patterns, + + c d + + sequences sum and a looked and terms geometric the have series: … … + + 26 244 2764.8 there of other Are types mathematical + sequences 196.83 and and + sequences + series. + 65.61 series series? + … + 0.01 used? How are they Example GDC For the geometric series 3 + 3 2 + 6 + 6 2 + ... , determine the Plus value of n for which > S help on CD: demonstrations least and Casio Alternative for the TI-84 FX-9860GII 500 GDCs n are on the CD. Answer An u = 3 and r = 2 Substitute the known old Indian fable values 1 tells into n the S us that a prince for mula. n 3 2 ( 1 ) Enter S = > the S 500 was so new game taken that he with the equation n n 2 1 into the of chess GDC. asked its Remember: inventor On the the number GDC, the X represents ter ms, and reward. The man f1(x) said represents choose ‘n’, his of to he would like S n one Look at the TABLE to grain rst the chess sums of the first n four etc., number This to of the first of the first 13 12 456.29, ter ms the ter ms is and on ask the doubling each seemed that the time. so the little prince is agreed approximately on ter ms. third sum on of board, grains second, The rice square see two the of the the straight away. sum Ser vants star ted bring rice to approximately the – and 648.29 to the prince’ s surprise soon n = 13, since S > the great grain overowed the 500 chess 13 board to ll the palace. When the sum of a geometric series includes an exponent n, How you can use logarithms. rice many did have Example A the the of prince give the man? geometric Find to grains progression value of n such has that first S term = of 0.4 and common ratio 2. 26 214 n Answer n 0 S 4 (2 1 ) = = 26 214 n 2 1 n 0 4 (2 1 = ) 26 214 n 2 – 1 = 65 535 n 2 n = 65 536 = log (65 536) Express this using logarithms. 2 log n 65 536 log n Use the change-of-base rule and your = = 2 GDC to find this value. 16 Chapter Exercise For 1 J each series, determine the least value of n for which S > 400 n 25.6 a 57.6 … + b 14 d 0.02 + – 42 + 126 – 378 … + + 0.2 + 2 + … geometric Find + + A 38.4 + c 2 + the series common has third ratio term and the 1.2 and value of eighth term 291.6 S 10 In 3 a geometric series, S = 20 and S 4 Find the common EXAM-STYLE = 546.5 7 ratio, if r > 1 QUESTION 4 Find a the common ratio for the geometric + series Hence, b find the least value of n such that S > ‘Hence’ + + tells you to use previous 800 your answer in n this In 5 6 a geometric sum of In geometric a the . the sum series, first of 6 terms series, the first Investigation 2 a are three + + 1 240 c For 1 – 60 each i F ind ii Use + + of – Find the the If r three sum first > 1, and terms of four find the GDC Do 2 you Now 3 the full notice use ten to the terms. times Extension material Worksheet 6 - on CD: Finance ratio. infinity series series. 75 + 30 + 12 ... + ... + to ratio, r calculate values any your is and seven common the values of S , S 10 Write 304, first terms the sums is series: common your first converging 3.75 these the the of terms. b – sum series … 15 of 1330. the geometric 0.5 sum is two Convergent Here the par t. you see patterns? GDC to on Why calculate your do the GDC you think value of , S 15 . 20 screen. this S is for happening? each series. 50 Do For you each think of the your calculator series in the is correct? investigation Explain you why or why not. should Paradox have noticed that the values of S , S 10 close. This series has is because when a and S 15 are ver y 20 Suppose 30-metre a common ratio of |r| < 1, the as n the value large. is term increases. actually In each the of This the decreases means sum approaching We call series 2 + approaching Patterns, some geometric 4 1 + as 0.5 n sequences + as ver y you such 0.25 ver y series + closer add little. constant series gets and (becomes that, changes are walking down a … , large. to zero) more The value as hallway. sum as n terms, is gets of walk the half might to reach Will you ever ver y suspect that the the hallway. you these convergent series you Ever y ten seconds, difference you between you geometric sum distance How the get long end of there? to will the the it end take hallway? If you tr y to find S on the GDC, you get: 50 50 = 4(1 – 0.5 ) = 4 Is the sum decimals the actually like rounded 4? NO! The 3.999 999 999 99 value Convergent of GDC to fit rounds on its the last screen, so digit all of you long see is 4. series The sum of the terms of a geometric series is IMPORTANT! This is only true geometric As or n n gets → ver y large, you can say that n ‘approaches and < only 1, then as n → ∞, r → 0, so then 1 series, when (Remember , |r| infinity’, ∞ n If for < r if < | r | | r | < < 1. 1, 1.) We can write this as: ⎛ ( ) ⎞ ⎜ ⎟ , = or ⎜ →∞ ⎟ ⎝ This means = ∞ ⎠ that as n gets ver y large (it approaches infinity), the We say ‘The limit of value of the series is n . approaching The series is converging to u 1 (1 r ) as the 1 value . We write this as S , and call it ‘the sum to n r infinity’. ∞ approaches innity is u 1 equal to ’. 1 r ➔ For a geometric series with |r| < 1, = ∞ Example For the series 18 + 6 + 2 + …, find S , S 10 and S 15 ∞ Answer 1 u = 18 and r = 1 3 10 ⎛ ⎞ ⎛ 1 ⎞ 18 ⎜ 1 ⎜ ⎟ ⎟ ⎜ 3 ⎝ ⎟ 1 ⎠ ⎝ S ⎠ Substitute = u = 18 and r = 1 10 1 1 n u 3 (1 r ) 1 into for mulae S the = and n ≈ 26.999 542 75 1 r u 15 ⎛ ⎛ 1 ⎞ 18 ⎜ 1 ⎜ ⎜ ⎝ ⎟ 3 S = ∞ 1 ⎟ r ⎟ ⎠ ⎝ S 1 ⎞ ⎠ = Write down all the digits from the 15 1 GDC 1 display. 3 ≈ 26.999 998 12 18 = S = 27 ∞ 1 ⎞ ⎛ ⎜ ⎝ 1 ⎟ 3 ⎠ Chapter Example The sum sum to Find of the infinity the first first is three terms of a geometric series is 148, and the 256. term and the common ratio of the series. Answer 3 u 1 S (1 r ) = This = 148 is the equation for S 3 3 1 r u 1 S = Multiply = 256 both sides of this equation ∞ 1 r 3 by (1 – r ) 3 u 1 (1 r ) 3 = 256 1 (1 − r ) The left side of this equation is now r identical to the left side of the S 3 equation. 3 256 (1 r ) = 148 Set 148 the right equal to Solve for sides each of these equations other. 37 3 1 − r = = 256 r. 64 37 27 3 r = 1 − = 64 64 3 r = 3 4 Substitute r = into the equation 4 u u 1 = 256 1 S = = 256 ∞ 3 ⎛ ⎜ ⎞ 1 1 r ⎟ 4 ⎝ ⎠ u 1 = 256 ⎛ 1 ⎞ ⎜ ⎝ ⎟ 4 ⎠ 4u = 256 1 u = 64 1 Exercise 1 Explain a 2 K how convergent Find S , S 4 a 144 you if a geometric series will be series. and S 7 + know for each of these series. ∞ 48 + 16 + ... b 500 + 400 + 320 + ... What real-life c 80 + 8 + 0.8 + ... d situations might be modeled 3 A geometric series has series? and = S ∞ = 13. Find S 3 5 EXAM-STYLE 4 For a QUESTION geometric progression with u 3 Patterns, sequences and series = 24 and u 6 = 3, find S ∞ by covergent In 5 a geometric progression, u = 12 and S 2 EXAM-STYLE A 6 The 7 sum and the seven . of such If a a 250. of sum to has Find the first of of u 1 is ratio of 0.4 and a sum to term. terms of 4374. the $1000 annually , will be interest a geometric Find the sum series of is the 3798, first in is the patter ns and a account savings makes account amount at the star t of in at the the the no many other ten after situations, pays or interest at deposits, years? each (Multiply account which withdrawals annually of real-life growth. account after end year. in population compounded the amount geometric patterns in and in The of geometric amount 1.04.) first five interest deposits 4% much When common the infinity compound person rate a arithmetic examples as how series Applications see Find terms. and We 64. QUESTION geometric infinity = ∞ (once year the 10 per will year), be 104% previous years the of amount the by would 10 be ≈ 1000(1.04) Y ou can each think year as of a $1480.24. the amount geometric of money sequence in with u the = account 1000 and at r = the end of 1.04: 1 u = $1000 = $1000(1.04) = $1040 = $1040(1.04) = $1081.60 = $1081.60(1.04) 1 u 2 u 3 u ≈ $1124.86 4 and Now so consider on. what happens when interest is compounded In more than once each year. questions the is term like ‘per sometimes this, annum’ used Let rather A = the amount of money in the = the interest n = the number of times t = the number of years p = the principal you can find the rate (a percentage, (initial amount of per year amount money ‘annually’ account or r than written that of in as a interest ‘once a year’. decimal) is compounded money) the account using the formula: nt r ⎛ A = p ⎞ + ⎜ ⎝ ⎟ n ⎠ Chapter Example APR A person deposits $1000 in an account which pays interest at 4% means percentage compounded quar terly . Assuming the person makes no or deposits, how much will be in the rate’. 4% additional APR withdrawals ‘annual APR, account after is the same as ten 4% per annum. years? Answer 4(10) 0.04 ⎛ A = 1000 ⎞ 1 + ⎜ Substitute ⎟ the known values into the What 4 ⎝ ⎠ other types nt r ⎛ for mula A = p 1 ⎞ of + ⎜ mathematics are ⎟ 40 = 1000(1.01) n ⎝ ⎠ useful ≈ $1488.86 This equation annual interest up 4 into and so 1%. If times the interest Example The is year 10 rate for is the divided each quar ter, interest rate compounded (quar terly) years, will because (4%) one quar terly ever y of rate par ts, interest period Population works this be is four for a quar terly applied 40 times. growth population of a small town population at the star t of 1980 population at the star t of 2020? increases was by 12 500, 2% what per is year. the If the predicted Answer 40 12 500(1.02) ≈ 27 600.496 At the star t population previous The be population approximately In questions of years, In like rather Exercise 1 of an the town will From 27 600 have Example than as a 23, term you need if u 1 2 A = cup five cups How high b How many metre Patterns, star ting 2020, 40 the of the population. years will passed. to think of n as the number sequence, u = 15 cm high. 3u 4 50 is a 1 to year, 102% 8 plastic When year’s 1980 be L arithmetic u each number. 6 Find of will 12 cm are stacked would cups high. a stack would high? sequences and series together, of it 20 take the cups to stack is stand? make a stack at least in nance? 3 George at 6% or 4 deposits APR. deposits, $2500 in Assuming how an he much account makes will be no in the a interest is compounded annually b interest is compounded quar terly c interest is compounded monthly? An arithmetic sequence is defined which pays additional account by u = interest withdrawals after 12n – 7 8 years and if the a n n geometric sequence is defined by v = – 1 0.3(1.2) n Find the least number of terms such that v > u n 5 In a geometric sequence, the first term is 6 n and the common This ratio is 1.5. In an arithmetic sequence, the first term is 75 and question v , rather than n common difference is 100. After how many terms will the sum the terms in the geometric sequence be greater than the sum term of 6 the At of terms the the beginning fish What in in the will of lake be the arithmetic 2012, is a lake expected number sequence? of to contains in the , to of the the nth geometric sequence. increase fish u n represent of uses the 200 at a lake fish. rate at The of the number 5% per beginning year. of 2015? 7 The population increasing continues at to population a of a rate city of increase of the is 275 000 3.1% at city per this to year. rate, reach people. The Assuming how long 500 000 will population the it is population take for the people? 2 8 A series has the formula S = 3n – 2n n Find a the values of S , S 1 Find b the values of u , u 1 Write c an expression and S 2 3 and u 2 for 3 u n n 9 A series has the formula S = + 2 2 – 4 n a Find the values of S b Find the values of u , S , u 1 1 Write c an expression and S 2 3 and u 2 for 3 u n 10 Two species population 1.25% is per of 3% species at population species B? 11. annual Mohira interest, which of rate is Mohira a remote 12 000 of 175 A be invests in an of spiders $3000 Ryan annual interest, neither person his de posits, account than how B is an the at a rate 50 000 month. than of and When will population account which but has much Mohira increasing invests 3% or in The which of pays yearly. Assuming withdrawals is each account yearly. island. species g reater compounded $3000 and population species interest, pays inhabit A The compounded also in a invests monthly. have spiders month. decreasing the 11 of is in 3% $3000 in annual an account compounded made more has pays any money hers after additional does ten Ryan years? Chapter . Pascal’s triangle and the binomial expansion Pascal’ s named Now we will look at a famous mathematical patter n known triangle. Here are rows 1 to 7 of Pascal’s after is Blaise as Pascal Pascal’s triangle (French, triangle. 1623–62). 1 1 3 1 1 Any number numbers in immediately 3 4 7 4 35 triangle above 1 6 21 Pascal’s 1 1 35 is 21 the sum 7 of 1 the Can two the it. 8th Y ou and generate adding wanted It to would Here are the numbers pairs find be ver y the of the in the numbers numbers to in triangle get the time-consuming numbers in the 4th the row . row? make row star ting next 15th to by of a the Or at But the the what 27th triangle can also be that triangle, 1, using combinations , found row will in what the be? if we row? big! 4, 6, 4, 1. C numbers predict top n These you numbers or is commonly r the ⎛ n ⎞ C n function on the GDC. written as r ⎝ C 4 = 1 C 0 4 = 4 C 1 4 = 6 C 2 4 = 4 C 3 4 = ⎟ ⎜ r , or ⎠ 1 n 4 sometimes as C r ⎛ ⎞ n ⎜ ⎝ ⎟ , or , C represents the number of ways n items can be r ⎠ taken r labeled at a A, time. B, C, For D example, and E. If suppose you reach a in bag contains and take 2 5 balls balls from the bag, there are = 10 different combinations of balls you could select. These combinations CE DE. are AB, AC, AD, AE, BC, BD, BE, CD, Make or how sure to use you the know nCr ⎛ ⎞ Y ou can find the values of expressions like ⎜ ⎝ a ⎟ without function using on GDC. ⎠ calculator. ➔ The is number found of combinations of n items taken r at a time by: ! is the sign. ⎛ ⎞ ⎜ ⎝ ⎟ The Patterns, expression , = ⎠ factorial ( where n! = n × (n – 1) × (n – 2) × … × 1 n! is called ) factorial’. your sequences and series ‘n Example ⎛ 7 ⎞ Find the value of ⎜ ⎝ ⎟ 5 using the formula, and check with your GDC. ⎠ Answer Substitute 7 5 n = 7 and r = 5 7! into 5!7 the for mula. 5 ! Y ou 7 × 6 × 5 × 4 × 3 × 2 ×1 Cancel = 5 × 4 × 3 × 2 ×1 out like factors may used 2 ×1 the numerator and the see dots from instead multiplication 7 × 6 of denominator. signs. 42 = = 2 ×1 = For 2 example: 3 · 3 × 2 · 1 for 21 Remember, we can also 2 × 1 ⎛ 7 ⎞ ⎜ ⎝ = ⎟ 5 find 21 ⎠ the value using Pascal’s triangle. Using the calculator: On the TI Nspire, Probability, nCr is on Combinations the menu. GDC help on CD: demonstrations Plus and GDCs Exercise Find each value using the ⎛ ⎞ formula, and check ⎜ ⎠ ⎝ ⎟ 5 ⎜ 6 ⎝ Investigation Expand as a 7 each of the – (a Do GDC. 3 ⎜ ⎟ ⎝ ⎠ patterns following how long it takes you in expressions to + ⎠ polynomials (write + 2 you Based 5 your answers notice on each each expression expansion. (a + 3 b) 3 (a + b) 6 (a + b) 5 b) at do 2 b) 4 Look your ⎛ ⎞ 6 ⎟ 1 (a 4 with polynomial). Time 1 CD. ⎠ ⎛ ⎞ 9 the C 3 ⎟ C 4 on TI-84 ⎛ ⎞ 2 ⎝ are the FX-9860GII M 1 ⎜ Casio Alternative for any these (a + and note similarities patterns, 6 b) any to patterns Pascal’ s predict what you see. triangle? the expansion 7 of (a + b) might be. Chapter Binomial We will expansion look at what happens when we expand an expression like n (a + In b) the , where n is a Investigation positive on page integer. 185, you expanded these expressions. 1 (a + b) = a 2 (a + b) (a + b) = a = a 3 + b) (a + b) you = a = a 2ab + 3a + b 2 2 b + + 4a + 5a number + 6a b + 10a + 3 terms 3 b each b 2 b at of + 2 4 closely 3 3ab 3 5 look The 1 2 + 4 5 If b 3 4 (a + 2 4 4ab + 2 2 b + 10a 3 b expansion, is one b 4 + 5ab you greater 5 + will than b see the some value patter ns: of n For example, when n The 2 powers of a begin 0 until you reach with a , and (a a = 1) in the 0 The 3 powers of b the powers of a decrease by 1 0 begin with b last n = 4, has term. 5 the expansion terms. 0 (b = 1), and the powers of b n increase by 1 until you reach in b the last term. 4 (a 4 The coefficients are The coefficients of all numbers from Pascal’s triangle! of Pascal’s the formula The 5 triangle. for exponents + are can numbers find combinations, in each 2 b The b) Y ou b) 2 6a n (a + term or add these the to from using nCr the the the nth power of on the a 3 + 4a 3 + 4ab b + 4 + b coefcients 1, 4, row triangle, function 4 = the 6, 4, 1 are the of Pascal’ s In (a 4th row or triangle. GDC. binomial. 5 3 For example, in the expansion (a + b) 3 = 2 a + 3a 2 b + 3ab + b) the 3 + b , coefcients the exponents in each term add to 3. 6 Y ou can use these patter ns to expand the expression (a + b) 10, 10, 5, 5th row of 1, 1 5, are the Pascal’ s . triangle. This expansion The powers The coefficients (1, 6, 15, of 20, will a have will will 15, 6, These (a + be patter ns the 6th the powers row of of b will Pascal’s increase. triangle 1). 6 = b) terms. decrease, 6 Therefore, 7 and 5 a + 6a 4 b + 15a obser vations 2 b can 3 + 20a help 3 b you 2 + to 15a 4 b 5 + 6ab understand 6 + b the + general ➔ binomial The theorem binomial where n ∈ for theorem expanding states that powers for any of n ∈ a positive means that power of a binomial, , ⎛ ⎞ + ⎛ ⎞ = ) ⎜ ⎝ ⎟ ⎛ ⎞ − + ⎠ ⎜ ⎝ ⎟ ⎛ ⎞ ⎠ − + ⎜ ⎝ ⎟ + ⎠ + ⎜ ⎝ ⎟ used in many mathematics Y ou can also write the binomial expansion using sigma areas of beyond ⎠ binomial including Y ou are the ➔ is integer . Combinations ( n binomials. can theorem, probability. even use notation: combinations to ⎛ ⎛ ⎞ ⎞ calculate ( + ) = ∑ Patterns, = sequences ⎜ ⎜ ⎝ ⎟ and ( ) ⎠ series ( ) your chance ⎟ of winning the lotter y! Example 5 Use the binomial theorem to expand (x + 3) . Write your answer in its simplest form. Answer Substitute ⎛ 5 ⎞ 5 ( x ⎛ 5 ⎞ 5 + 3) = ⎜ ⎝ ⎟ 0 x ⎟ 1 ⎝ )(1) + (5)(x 4 + ⎜ + 3 + ⎜ ⎠ ⎟ 2 ⎝ x )(3) + (10)(x ⎛ 5 ⎞ 2 2 3 + ⎠ ⎜ ⎝ 3 3 15x ⎛ 5 ⎞ 1 3 x 4 5 = 4 + ⎠ 5 = (1)(x ⎛ 5 ⎞ 0 3 x ⎟ 3 1 + ⎝ 2 )(9) + (10)(x ⎜ ⎠ ⎟ 4 4 x 0 3 + ⎠ ⎜ ⎝ ⎟ 5 x binomial + )(81) + (1)(1)(243) You should find these with 270x + 405x + theorem. ⎠ 2 90x the 5 3 1 )(27) + (5)(x into ⎛ 5 ⎞ 3 3 x and be able values to both without your 243 GDC. Example 3 Use the binomial theorem to expand (2x – 5y) . Write your answer in its simplest form. Answer ⎛ 3 ⎞ 3 (2x 5 y = ) ⎜ ⎟ 0 ⎝ 3 ⎛ 3 ⎞ 0 (2x ) 5 y ( + ) ⎜ ⎠ ⎟ 1 ⎝ 2 ⎛ 3 ⎞ 1 (2x ) 5 y ( + ) ⎠ ⎜ ⎟ 2 ⎝ 1 (2x ) Be careful an expression 5 y ) + ⎜ ⎝ ⎟ 3 0 (2x ) 5 y ( to (1)(8x ) 2 )(1) exponent be the 8x + (3)(4x 2 )(–5y) + (3)(2x)(25y ) 3 + (1)(1)(−125y applied Exercise Use the 2 − 60x . needs variable y 2 + 150xy ) 3 − to both and the coefficient! 3 3 (2x) 3 3 = see 3 ⎠ = you like ⎠ The ⎛ 3 ⎞ when 2 ( (2x) 125y 3 = 2 x 3 3 = 8x N binomial theorem to expand each expression. ⎛ 5 (y 1 + 4 3) (2b 2 – 1) (3a 3 + 2) + 4 ⎞ 6 ⎜ ⎟ ⎝ ⎠ ⎛ 8 (x 5 + (3a 6 – 2b) 7 8 ⎝ Sometimes, you binomial. Example Y ou will not may need simply the be entire looking the ⎟ ⎜ ⎠ ⎝ expansion for one of a 4x ⎞ ⎟ 2 y power par ticular + ⎠ of term. 3 Find 2 + ⎜ a ⎛ ⎞ 4 y) x 9 term in the expansion of (4x – 1) 3 Answer In order to get x the binomial, 4x, to the third power . So ⎛ 9 ⎞ ⎜ ⎝ ⎟ 6 , raise the first term of 3 ( 4 x ) 6 ( 1) the second term of the binomial, –1, ⎠ will be raised to the sixth power . You 3 = ( 84 ) ( 64 x ) could use 3 = ⎛ 9 ⎞ ⎛ 9 ⎞ (1) ⎜ ⎝ ⎟ 3 instead of ⎠ ⎜ ⎝ ⎟ 6 as these ⎠ 5376x values are equal. Chapter Example n In the expansion of (2x + 1) 3 , the coefficient of the x term is 80. Find the value Answer n ⎛ You ⎛ n ⎞ ⎜ ⎝ ⎟ 3 3 (2x ) n 3 could have = ⎝ 80 x of ⎜ ⎝ 3 ⎟ ⎜ ⎟ ⎛ 3)! 3 3 , as these ⎠ values ⎛ n ⎞ ⎜ ⎟ ⎜ ⎟ ) (1) = 80 x Use the equal. n! 3 (8x are ⎠ for mula ⎠ ⎝ r = r !( n r )! ⎠ ⎞ n! ⎟ ⎜ ( 8 ) = 80 As you only have to find the coefficient, you can ⎟ ⎜ ⎝ ⎟ ⎞ n! ⎜ ⎝ ⎟ n ⎛ n ⎞ instead (3 )! ( n n. ⎞ ⎜ 3 1 ⎠ ⎛ used of (3 )! ( n 3)! ⎠ 3 leave n × (n − 1) × ( n − 2) × ( n − 3) × ( n − (8) (3 × 2 × 1) × ⎡ ( n n × − 3) × ⎣ (n (3 − 1) × ( n (n − 2) × × 2 × 1) × ⎡ ( n ⎣ − the x = 80 = 10 Divide both sides by 8 4 ) × ...⎤ ⎦ n − 3) × ( of f 4 ) × ... − 3) × (n n × − ( n − 4 ) × ... Simplify ⎦ (n by canceling out like factors from the 4 ) × ...⎤ − 1) × ( n numerator and the denominator. − 2) = 10 = 60 You can solve polynomial equations such as this 6 using n × (n − 1) × 3 n (n − 2) 3n + 2n – 60 = 0 = 5 O 5 1 Find GDC. 2 – n Exercise a the x 7 term EXAM-STYLE in the expansion of (x – of (4y 4) QUESTIONS 4 5 2 Find the y term 3 Find the a 4 Find the constant 2 in the expansion – 1) 4 b 6 term in the expansion of (2a – 3b) 9 term in the expansion of (x – 2) The is 6 5 In the expansion of (px + 1) ‘constant just the value of the coefficient of the x term is 160. p 7 6 In the Find expansion the value EXAM-STYLE of of (3x + q) 5 , the coefficient of the Find the x term is q QUESTION 7 constant term in the expansion of 8 Find the constant term in the expansion of In the QUESTION n 9 EXAM-STYLE expansion of (x + 1) 3 , the coefficient of the x term is 2 two times Patterns, the coefficient sequences and of series numerical 3 , term Find the term’ the x term. Find the value of n 81 648. with no variables. n 10 In the expansion of (x + 2) 3 , the coefficient of the x term is two 4 times the coefficient Review of the term. x Find the value of n exercise ✗ EXAM-STYLE 1 Consider a Write b Find QUESTIONS the arithmetic down the u sequence common Find c 3, 7, 11, 15, ... difference. the value of n such that u 71 2 The first three a Write c Find = 99 n terms down the of an value infinite of geometric r. Find b sequence are 64, 16 and 4. u 4 3 In an the sum to arithmetic infinity sequence, of u this = sequence. 25 and u 6 4 a Find the common difference. b Find the first of Consider a Find the the term the arithmetic value of 49 sequence. sequence x. = 12 22, x, Find b 38, ... u 31 5 Evaluate the expression ∑( 6 Consider a 7 Find Find all the the geometric common possible geometric: x, EXAM-STYLE 12, series 800 ratio. values 9x, ) = of + such + Find b x 200 that 50 the this Find 9 A the b x top row store in the How are In an first a ... the EXAM-STYLE 2 Consider a Find the a expansion display three cans, of of (2x soup and each + 3) cans row stacked has two in a pyramid. more cans than 35 cans in the bottom row , how many rows are cans 63 is series, in the display in total? the first term is 4 and the sum of the value of the 1000. common difference. Find b the 17th term. QUESTION the u are exercise terms Find is it. arithmetic 25 infinity . display? many Review 1 in has has above there to 5 row If sum QUESTION term grocer y The a the ... sequence 3 8 + . arithmetic b sequence Find the 3, value 4.5, of n 6, 7.5, such ... that S = 840 n Chapter 3 In an the arithmetic first 10 a Find the first b Find the sum EXAM-STYLE 4 series, terms In a is the tenth term is 25 and the sum of 160. term of and the the first common 24 difference. terms. QUESTIONS geometric sequence, a Find the common b Find the least the first term such that is 3 and the sixth term is 96. ratio. value of n u > 3000 n 5 In an arithmetic difference and the Find In a 50. least is 7 Find is first EXAM-STYLE the first geometric ratio greater terms the a value geometric first In common the sequence 6 is sequence, of is n than series, term is sequence, 28 the and first the common term is 1 1.5 such the the that nth 3rd the term term is nth of 45 term the of the geometric arithmetic and the sum sequence. of the 2735. term and the common ratio, r, if r ∈ QUESTION ⎛ 4 7 Find the term in x in the expansion ⎞ of ⎜ ⎝ ⎟ ⎠ 8 8 In the expansion of (ax + 2) 5 , the x term has a coefficient of . Find 9 the At the a If value If number according ● Each 6 In This a positive ● Y ou can u u = n or is a find + (n – population a the rate of beginning continues countr y at be of 1.6% this of a countr y was annually , 3.4 million. estimate the 2040. rate, expected in to what year exceed 7 would million? sequences is a patter n of numbers arranged in a par ticular order r ule. number, or element, of a sequence is called a term sequences arithmetic value at SUMMARY individual an at the sequence Arithmetic ● of and to the grows growth population Patterns A 2010, population CHAPTER ● of population population the a beginning the countr y’s b of sequence, called the negative the nth the terms common increase dierence , or or decrease d. The by a constant common value. difference can Patterns, a value. term of an arithmetic sequence using the formula: 1)d 1 Continued be sequences and series on next page Geometric ● In a sequences geometric term by a sequence , constant value. each This term value can is be obtained by multiplying the common ratio, called or the previous r. n ● Y ou can find the nth term of a geometric sequence using the formula: u = u n Sigma (∑) notation and – (r 1 ) 1 series ● ∑ means the sum of the first n terms of a sequence. = Y ou read this ‘the sum of all the terms u from i = 1 to i = n’. i Arithmetic ● Y ou can find series the sum of the = ( + or ) = can + of an arithmetic series using the formula: ( − ) ) series find the sum of the first n terms of a geometric series using the formula: ( terms Geometric Y ou n ( ● first ) = or ( ) = , where r ≠ 1. Convergent series and sums to infinity ● For a geometric series with < , = ∞ Pascal’s ● The triangle number of ⎛ ⎞ ⎜ ⎝ ● The ⎟ , ⎠ ( + can n items taken r expansion at a time is found by: where also ⎟ = n × states that (n for ⎛ ⎞ ⎜ n! – 1) × (n – 2) × … × 1 ) ⎛ ⎞ = ) theorem ⎝ Y ou of binomial ● the combinations = binomial ( and ⎠ write − + ⎜ ⎝ the ⎟ power of a ⎛ ⎞ any ⎠ − + ⎜ ⎝ binomial ⎟ where n ∈, ⎛ ⎞ binomial, + + ⎠ expansion ⎜ ⎝ using ⎟ ⎠ sigma notation: ⎛ ⎛ ⎞ ( + ) = ∑⎜ = ⎜ ⎝ ⎝ ⎟ ⎠ ( ) ( ) ⎞ ⎟ ⎠ Chapter Theory of knowledge Whose Pascal's triangle idea is named after was it the This Frenchman Blaise Pascal, anyway? who is not the long-standing about it in 1654 in his Treatise rst case of a relatively wrote on mathematical idea being the attributed to a par ticular person. This Arithmetic Triangle has often happened mathematician However, the proper ties of this known and studied other par ts before of in the Pascal's India, world work, China for China, Throughout have time. Pascal's triangle is called triangle' after a been 13th but it Do you was known In the to the given or centur y , the credit think that Omar seen have been 's in Khayyám Pascal's triangle? gl used? an ngle 1 1 1 1 1 [ 1 Theory of 6 15 knowledge: 20 15 Whose idea for mathematical of these attributed person? triangle. mathematicians many Persian oet a public. inventions. this. 11th the years, long wrong before introducing idea centur y ideas mathematician, an 'Yang Hui's well-known and centuries discoveries In a by mathematical mathematicians when published patter n impor tant were has 6 was 1 it anyway? Blaise Pascal (1623–62) to the In Fibonacci: patterns nature The Italian Leonardo sequence in If mathematician of Pisa, in his Liber the F ibonacci Abaci, published 1202. set begin month diagram shows how the this problem: sequence was with each which becomes month on, produced F ibonacci The he you each F ibonacci, introduced book it in not the only how in a a single pair pair produces productive many of a from pairs of rabbits, new the and pair second rabbits will be year? mathematician to work with this pattern. Number grows. of pairs 1st month: 1 pair of original two rabbits 1 2nd month: still 1 pair as they are not yet productive 3rd month: 2 pairs new 4th month: 3 pair pairs they – original they – original pair produced in and the 1 produce produced month, pair in pair , pair 2 3rd they 4th 3 month The the number of F ibonacci pairs gives sequence 5 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, , , where , ... each term i een sequence Could it appears be that mathematics in nature? there and is a relationship between nature? How are Pascal's triangle F ibonacci sequence the of and related? the Hint: look at { sums the diagonals in the triangle. .1250) Chapter Limits CHAPTER derivatives OBJECTIVES: Informal 6.1 ideas of limit and convergence; ⎛ from and rst principles as f ′( x ) = lim f (x + ⎜ h ⎝ normals, interpreted and their as gradient notation; Denition of derivative ⎟ h→0 Derivative limit h) − f ( x ) ⎞ ⎠ function and as rate of change; T angents and equations n Derivative 6.2 of x (n ∈ ); Differentiation of a sum and a real multiple of these x functions; product Derivatives and quotient of e and r ules; ln x; The The second chain rule for derivative; composite use of both functions; forms of the notation, 2 d y and f ″ (x) 2 dx Local 6.3 maximum gradients; graphs Before 1 f, Factorize and an behavior f ″; problems + of involving Points functions, Optimization how and of inexion including s, zero and relationship v and Expand between acceleration 1 the a Factorize: 2x = 2x (x 4 + 2x + 1) a 9x 3 − 15x 2 + 3x 4x b 2 2 non-zero check 2 + the velocity Skills expression. 4x with applications displacement to: 2 2x points; start know 3 e.g. f ′ you should minimum Graphical Kinematic 6.6 Y ou of and binomials. c − 9 − 9x 2 x − 5x + 6 2x d − 5 4 e.g. Expand (2x − 1) 4 (2 x 2 − 1) Expand each binomial. 1 3 a 4 = 1( 2 x ) 0 ( −1) 3 + 4 (2 x ) 1 1 1 2 + 6( 2 x ) 2 1 ( −1) + 4 (2 x ) + 4 2) (3x b − 1) 3 (2x c 1( 2 x ) 2 1 3 3 3 1 Use rational exponents to rewrite 4 ( −1) 1 4 = 16 x 3 − 32 x 4 6 4 1 expression in 2 + 24 x − 8x the b x x rational exponents to rewrite 7 d 7 5 x e n expressions in the form 1 2 5 e.g. = 2x 2 ; x = 5 x Limits and derivatives x cx cx c 3 6 Use form 4 1 + 1 a 3 3y) 3 n + + ( −1) 1 0 (x 1 ( −1) 3 x 5 x each If you pluck quieter as a string time on passes. a guitar This can and be let it vibrate, modeled by the the sound gets function sin t f (t ) , = where t represents time. As t becomes larger and larger, t sin t becomes closer to zero – this is the limit value of the function. t sin t We write this as = lim t →∞ calculus. is a sine Y ou wave, Calculus is geometr y problems. variable in the lear n a later branch together that evaluate is are a fundamental concept of about mathematics the limit calculus sine and that process uses function, whose focus to In on algebra looks find calculus change. then takes and limits Integral repeated limits the graph chapter. changing. involve basic Limits more of with Differential quantity problems to will 0. t this at the uses and two rate limits chapter differential we types at of which to a solve will lear n calculus. Chapter . In Limits this section convergence basis of and you and convergence will use a with pair the notation. concepts The of concept limits of and limits is the calculus. Investigation Work investigate limit of a par tner . scissors Round – Y ou and Por tion number creating a need copy of the will the end of one this paper of sequence rectangular piece of paper , table. you the Fraction a have at round Decimal (3 sf) 1 2 3 4 5 6 Round 1: roughly table. as Cut the equal size. Record both Round a 2: rectangular the fraction Cut T ake one por tion the and a of piece piece the piece paper each, original decimal ‘spare’ of (to of into leaving three one rectangle three paper piece you signicant into three pieces now on When cutting of paper into the size Each of you add one piece of this to your pieces por tion of of have, in Repeat As 1 Record the the you the same same total way as of the original rectangle say about more the you If you repeat this you Limits of of the for four and por tion more more of process original not just more rounds of now the activity say the rounds. you could rounds of this activity, what the original rectangle you forever , what can you say rectangle you number of rounds approaches innity. Can you give can example in real life have? about grows or develops the like por tion complete more that 2 do original an you you exact, before. process complete por tion be equal the and rectangle. to equal approximate. gures). As size. pieces have have the three this? have? sequences The notation lim u = L n n→∞ The data you collected in the investigation forms a sequence, is where is u the por tion of the rectangle you have after round 1, 1 u the por tion you have after round 2, and so on. n of read ‘the approaches u 2 equals limit as innity L’. n Sequences like this are called convergent because as the The term number in the sequence increases, the terms in ancient the approach sequence. a We fixed can value write known this as: the limi t, as lim u = Greeks the used sequence of as L, L n the limits to using the idea nd of areas, ‘method of n →∞ Sequences that are not convergent are divergent exhaustion’. wish What is Limits the limit of the and derivatives sequence formed in the investigation? to Y ou research may this. Example Determine If a sequence 0.3, a whether 1 c 0.33, 6 , 5 is 31 0.3333, 156 , 125 sequence convergent, 0.333, , 25 each give is the convergent limit … of the or divergent. sequence. b 2, 4, 8, d 1, −1, 16, … 781 , , 625 ... 1, −1, . . . 3125 Answers 1 The Convergent; a lim u patter n indicates = Other n n →∞ 3 that the sequence notations for is recurring decimals approaching 0 include 0.333 3…, or 3, 0 3 which 1 is the decimal for m of 3 Divergent b Each ter m, ter m so in they the are sequence not is larger approaching than a the previous limit. 1 lim u Convergent; c = To n n →∞ compare fractions with dif ferent denominators, 4 use a GDC 0.248, to conver t 0.2496, them 0.249 92, to decimals: 0.2, 0.24, … 1 The values are approaching 0.25 or 4 Divergent d The two Exercise Determine If a 3, 5, 1 7, 3, 4, 3, f of (x ) = 3, is the 1 limit of 20 − , the or the and sequence are not are oscillating approaching a between fixed value. , 3.499, 182 , 27 162 divergent. sequence. 3.499, 121 4 ... 10 000 4, convergent 3.49, 2 1000 4, give … , 100 sequence convergent, , Limits lim is each 1 , − 10 5 whether 1 3 values in 7A sequence 1, 1 ter ms 1093 , 243 3.4999, 1640 , 1458 … , ... 2187 … functions L means that as the value of x becomes Y ou can use a GDC to help nd the x →c sufficiently f (x), close becomes to close c (from to a either fixed side), value L. the If f function, (x) does not limit of a function become close to a fixed value L, we say that the not and Y ou can examine graph the the values of limit f (x) does function. Graphically: when x is near c exist. Numerically: of values f (x) when and x is Y ou can examine near make the a table values of c Chapter Example Use a Find GDC the to limit examine or state each that it function does graphically not and numerically . exist. 2 x 2 a lim x b x →2 ⎧1 1 lim x →1 f lim c (x ) ; where f (x ) = for x ≥ 0 ⎨ x →0 x 1 ⎩ −1 for x < Answers 0 y 2 2 a lim x Plot the graph of f (x) = x a 7 f (x) 6 using x →2 GDC, and look at the values of 2 f(x) as x approaches 2 and from the from the right = x 5 left. 4 3 2 1 Graphically, f (x) approaches 4 as 0 –4 x approaches Numerically, 2 from either –2 –3 x –1 1 2 3 4 2: as x side, becomes f (x) close becomes to close to 4. → 2 ← x 1.8 1.9 1.99 1.999 2.001 2.01 2.1 2.2 f 1(x) 3.24 3.61 3.960 3.996 4.004 4.040 4.41 4.84 4 ← 2 To build variables the to table above using ‘Ask’. Enter the a GDC, values for enter f1(x) = x . Then set the independent x. GDC help on CD: demonstrations Plus and GDCs Casio are on Alternative for the TI-84 FX-9860GII the CD. 2 So, lim x = 4 x →2 The graph and table are shown on the same screen. 2 2 For f (x) = x we can substitute and find that lim x 2 2 4 x 2 { Limits and derivatives Continued on next page y 2 x b 1 lim x →1 f (x) x approaches 2 as x approaches 1: 7 1 2 x 6 f(x) – 1 = x – 1 5 4 3 2 1 0 –3 x –1 2 1 x Since division by zero is not defined, f (x ) is = when x − 1 = 0 or x = 1. Therefore there is a undefined 1 x discontinui ty in the graph 2 x when x = 1. Notice that f (x ) ( 1 = x + 1 )( x − 1 ) = x = 1 x x + 1, when x ≠ 1 1 2 x Even though f (x ) 1 is = x becomes close to 1 from undefined when x = 1, the limit exists since as x 1 either side, f (x) becomes → close to 2. ← 1 x 0.8 0.9 0.99 0.999 1.001 1.01 1.1 1.2 f (x) 1.8 1.9 1.99 1.999 2.001 2.01 2.1 2.2 → 2 ← 2 2 x x Note So, lim = that lim = x + 1 )( x − 1 ) x lim 2 x →1 x →1 ( 1 1 x x →1 1 x 1 1 = lim ( x + 1 ) = 1 + 1 = 2 x →1 f (x) c lim f (x ) does not approach the same value as x y where x →0 approaches ⎧1 f (x ) = for x ≥ 0 from the left and right: 2 0 ⎨ ⎩ 1 −1 for x < 0 0 –4 –3 –2 –1 x 1 2 3 4 –2 → x f (x) So, lim f (x ) does Note exist. ← −0.2 −0.1 −0.01 −0.001 0.001 0.01 0.1 0.2 −1 −1 −1 −1 1 1 1 1 that f (0) = 1, but lim f (x ) does not exist. x →0 x →0 not 0 This is close to because −1 for f (x) is values close of x to to 1 the for left values of x of = x to the right of x = 0 and f (x) is 0. Chapter Exercise Use and a 7B GDC to examine numerically . Find each the function limit or graphically state that it does Extension material Worksheet 7 look not An on CD: algebraic limits exist. 3 2 x 2 lim ( x 1 at - + 1) − 4 x + x lim 2 x →0 x →3 x 2 x − 3x 1 + 2 lim 3 x →4 x 2 ⎧x lim 5 lim 4 x →2 f ( x ); f where (x ) = + 3 x for x 4 ⎩ secant a circle the −x + 5 line to intersects ≥ 1 ⎨ x →1 A for x circle twice. < 1 2 ⎧x lim 6 ( x ); f f where (x ) = + 3 for x ≥ 2 ⎨ x →2 ⎩ x for x < 2 A tangent to a circle intersects . The tangent line circle and line the once. n derivative In this section we of will x work with secant, tangent A and normal lines. We will define the derivative tangent cur ve a function of cer tain and lear n some r ules for finding derivatives the functions. – secant and tangent may cur ve than Investigation line is the graph of f (x) = x + a intersect more once. lines 2 Here to of y 1 6 Copy 1 the graph to paper and draw lines AP, BP, CP, DP, 5 EP and FP. These lines are called secant lines to the 4 2 graph of f (x) = x + 1. 3 A 2 Copy and complete the F 2 table. B E P Gradient x 0 –2 Point Coordinates Line P — A AP B BP C CP or 1 –1 2 slope — Recall of a that line points the (x , y 1 ) y 2 (x DP , 2 y ) x 2 3 4 As E EP F FP points does the Draw the on the cur ve gradient line at of get the point P closer secant that and lines has the closer seem to to gradient point be you P, what value approaching? found in question 3. 2 This Limits line and is called derivatives the tangent line to the graph of f (x) = x + 1 at P 1 is 2 x the and 1 y D gradient through 1 Lines have gradient line to the Newton velocity a of constant a cur ve cur ve at worked of a Gradient a with a given that moving of gradient, at point. when object but point This he cur ves is gradient is the the wanted whose secant other to do concept find velocity the was not. of The the that tangent Sir Isaac instantaneous always changing. line y y f(x + = f(x) h) Q(x + h, f(x + h)) [ Sir Isaac Newton 1642–1727 , English mathematician, is one f(x) P(x, f(x)) of the mathematicians credited with x 0 x x + developing h calculus. h The gradient of the secant line PQ is written as The f (x + h) − f (x ) f (x + h) − f (x ) f (x + expression h) − f ( x) is = (x + h) − x known h h as the dierence quotient Example 2 Write an Simplify expression your for the gradient of a secant line for f (x) = x + 1 expression. Answer 2 f (x + h) − f ⎡( x (x ) + 2 2 + 1⎤ h) ⎣ − ⎦ ( x Replace the x in x ) + 1 + 1 = with h x + h to write an h expression 2 ( 2 x + 2 xh + for f (x + h) 2 ) h + 1 − ( x ) + 1 = 2 Expand (x + h) h 2 2 xh + h Combine = like ter ms. h h (2x + h Factorize. ) = h = Exercise Write an function. 2x Simplify. + h 7C expression Simplify 1 f (x) = 3x 2 f (x) = 2x 3 f (x) = x + for your the gradient of a secant line for each expression. 4 2 − 1 2 + 2x + 3 Chapter Gradient Suppose of that a tangent point Q slides line down and the the cur ve derivative and approaches y point y P. The secant lines PQ will get closer to the tangent line at Q(x f(x P. h As Q gets closer approaches 0 of to P, the h gets closer gradient of to the 0. We secant can line take to get = f(x) point the limit the gradient + + h, f(x + h)) h) as f(x) of the tangent line: P(x, f(x)) f (x + h) − f ( x) is lim f (x + h) − f h→0 (x ) not h x 0 x x + h lim a h →0 constant. It is a h h function that gradient of f gives at the x f ′(x) f ➔ The function defined (x + h) − f lim by is h →0 is read as: the (x ) known as the derivative of f x. f, or : h dy of derivative f. The derivative is defined prime of is read by dx f f ′( x ) = (x + h) − f (x ) dy lim f = or h →0 h (x + h) − f (x ) as the h →0 dx with h ‘d y respect d change that in to x’ or slope change in This is x 2 the derivative of f (x) = x + 1 and hence find the gradient of the Δy expressed tangent line when x = Δx dy y 2 ⎡( x + 2 + 1⎤ h) ⎣ ′( x ) = − ⎦ ( x Simplify ) + 1 lim h →0 = the Example 3. Evaluate the quotient as shown in h lim (2x + h = ) 2x limit by substituting 0 + 0 h →0 for f ′( x ) = 2x ′(3) = 2(3) f = h. The 6 derivative, f ′(x) So the gradient of the = 2x, when x = 3 is is a tangent function line that gives 6. the gradient of the 2 cur ve at Exercise the definition find the gradient 1 f (x) = 2x 2 f (x) = 3x 3 f (x) = x − 3; of of x derivative the = tangent 2 2 + 2x; x = −3 2 Limits f(x) any = x point + 1 x 7D Use lim x 0 dx f and − x + 2; x derivatives . as 3 Answer = 1 to find line at the the derivative given of value f of and x hence is y . Find of x’. Recall Example ‘derivative lim x y Some rules for derivatives n Investigation Use 1 the denition – of the derivative derivative to nd the of f (x) = derivatives x of Recall 2 f (x) = x 3 , f (x) = the denition 4 x and f (x) = x of derivative is n Make 2 a conjecture about the derivative of f (x) = x f ( x f ′( x ) Express your conjecture in words and as a function. + h) − f ( x ) = lim h →0 h 5 3 We is Use your Use the conjecture denition investigated tr ue ➔ for any Power only real to of predict derivative positive number = Example the derivative see if your values of f (x) = x prediction for n, but the was correct. following n. rule (x) Use f to integer n If the x power n−1 , then r ule to f ′(x) find = the nx , where derivative of n ∈ each function. 1 12 f a (x) = x f b (x ) = c f (x ) = x 3 x Answers Use 12 f a (x) = 12 f ′( x ) the power rule. x 1 = 12 x 11 = 12 x 1 3 b f (x ) = = Rewrite x using rational exponents. 3 x Use the power rule. 3 −3 −1 ′( x ) f = −3 x −4 = −3 x Simplify. = − 4 x 1 2 c f (x ) = x = x Rewrite 1 −1 1 ′( x ) = rational exponents. − 1 2 f using 1 x 2 = x Use 2 the power rule. 2 1 1 = Simplify. or 1 2 x 2 2x Exercise Find the 7E derivative of each function. 1 5 1 f (x) = 8 x 2 f (x) = x 3 f (x ) = 4 x 1 5 3 4 f (x ) = x 5 f (x ) = 6 f (x ) = 3 x x Chapter Using the power derivative of a ➔ of function f (x) Constant The f(x) ➔ = c is a = If Sum The f or cf is any or (x) of the The any a = the is two process real zero. which r ules of number, then has The a graph gradient of of the c is any real number, the f ′(x) = 0 constant function then y ′ = cf ′(x) rule constant times a function is the constant times the u(x) ± of a sum rule v (x) f ′(x) = u ′(x) ± v ′(x) rule function or then that difference is of the the sum or difference derivatives of the of two or more terms. each function. 5 2 4x + 2x − 3 f b (x ) = 3 4 x = find derivative zero. x + 8 3 f (x) can the function. 3 c we finding rule where dierence = line dierence Differentiate f (x) is constant multiple Example a c multiple (x), derivative terms following dierentiation where horizontal of Sum the rule of derivative derivative called c, Constant y and functions. rule Constant ➔ = derivative If The is Constant If r ule many (x − 2) (x + 4) f d (x ) 2 + 2x − 3 = x Answers 3 a f (x ) = 2 4 x + 2x Find − 3 3 −1 f ′( x ) = 4 (3x of 2 −1 ) + 2 (2x ) the the derivative constant of ter m each is ter m. Note the derivative the derivative 0. 0 2 = 12 x + 4 x 1 5 5 b f (x ) f ′( x ) = 3 x + 8 = 3x Rewrite + 8 1 exponents. − 3 5 3 ⋅ rational 4 −1 1 = using x 5 + 0 = 5 x Find the derivative of each ter m. Note 5 of 3 the constant ter m is 0. 3 = or 4 5 5 5 4 Simplify. x 5x 2 c f (x ) = (x − 2 )( x + 4) = x + 2x − 8 First expand so that the function is the sum or n 2 −1 f ′( x ) = 2x dif ference 1−1 + 2 ⋅ 1x − 0 = 2x of ter ms in the for m { Limits and derivatives ax + 2 Continued on next page 3 2 4 x f d (x ) 3 + 2x − 3 = 2 4x 2x = 3 + x Rewrite − x x 2 ′( x ) in the the for m function is the sum or dif ference of ax 1 4 x + 2x − 3x 2 −1 f that n ter ms = so x = 4 ⋅ 2x = 8x 1−1 −1−1 + 2 ⋅ x − 3 ⋅ ( −1) ⋅ x 3 2 + 2 + 3x = 8x + 2 + 2 x 3 2 8x + 2x + 3 or 2 x Exercise 7F Differentiate each function. 3 2 f 1 (x ) 3 = f 2 (x) = 5 f 3 (x ) = x − 2 8 x x 5 f 4 (x) = 3 2 π x f 5 (x) = (x − 4) f 6 (x ) = x − 4 x 3 3 4 f 7 (x ) = f 8 (x ) = ( 3 10 f (x ) = x (x ) = x normal x 11 f (x) 12 f (x) = 12 14 f 2 (x) = 3x − 2x − x + 3x 2 + 5 = 2x + 7 1 2 3 + 2x Equations The f ) 4 + 2 f 4 x 4 x 3 13 9 2 2 4 x of line per pendicular + 1 tangent at to a point the (x) 2x (x and on tangent = a at Normal 3x) normal cur ve line 2 − is the that line to 15 f (x) = (x + 3x)(x − 1) lines line point. cur ve [ y = f(x) Sparks created grinding wheel tangent the Tangent Example Write an line to by a are to wheel. cur ve equation for each line. 2 a The tangent b The normal c The tangent line line to to the cur ve the f (x) f cur ve = (x ) x = 2 + 1 x at the when point x = (1, 2) 9 27 and normal lines to the cur ve f (x ) = x + 2 2x when x = 3 3 d The tangent to f (x) = x 2 − 3x − 13x + 15 that is parallel to the [ tangent at (4, Spokes on a bic ycle −21) wheel { Continued on next page the are normal to rim. Chapter Answers To 2 a f (x) = x + find line, f ′(x) = the gradient of the tangent The symbol ∴ is used 1 find the derivative of f and to mean ‘therefore’. 2x evaluate m = when x = 1 ′(1) f tangent = 2(1) = 2 Use the write ∴ y − 2 = 2( x − 1) point the (1, 2) equation and of m the = 2 to The equation line through ,y 1 f (x ) = 2 the a point line. (x b of tangent Rewrite x the function using is rational with y = gradient m(x x 1 (See exponents. 1 ) m 1 y ). 1 Chapter 18, 2 = 2x Section 3.11.) If has 1 1 2 f ′( x ) = x or x m = f To ′(9 ) find the gradient of the tangent tangent line, find the derivative of f and 1 = evaluate when x = 9. a line gradient 9 m, the gradient of 1 the = perpendicular 3 1 line m = −3 Since the nor mal line is . m is normal (See per pendicular f (9 ) = 2 9 = the gradient a Use − 9) the write f on of the when point the taking the the gradient of (9, 6) equation nor mal x = and of line by 9 m the = −3 to tangent line. 27 c f (x ) = x + Rewrite the function using rational 2 2x exponents. 27 2 = x + x 2 27 f ′( x ) To = 1 − find the gradient of the tangent 3 x line, m = f find evaluate ′(3) the derivative when x = of f and 3 tangent 27 = 1 − 3 3 Since = the gradient is 0, the tangent line 0 is horizontal, so the normal line must 27 be f (3) = vertical. 3 + 2 2 (3 ) Find 9 a point on the lines by = evaluating f when x = 3 2 ∴ Normal line is x = 3 and 9 tangent line is y = 2 { Limits and Chapter derivatives Continued 18, line, line. point evaluating −3( x by reciprocal tangent Find = tangent Section the opposite − 6 the 6 find ∴ y to on next page 3.11.) 3 f d (x) = x 2 − 3x − 13x + 15 2 f ′( x ) = 3x − 6x f ′( 4 ) = 3( 4 ) − 13 2 Find − 6( 4 ) − 13 the when = 11 x gradient = of the tangent line 4 2 3x − 6x − 13 − 6x − 24 Set = 11 to 2 3x = the find derivative equal x-coordinates to of 11 points with 0 parallel tangent lines. 2 3( x − 2x 3( x − 8) − 4 )( x = + 2) 0 = 0 Recall x = 4, −2 Notice x = 4, point The that is the of 3 f ( −2 ) = − 3( −2 ) the values, x-coordinate x-coordinate for the of lines the given that have parallel the same gradient. (4, −21). of the point parallel line of is −2 Evaluate 2 ( −2 ) = of tangenc y tangenc y x one f at x = −2 to find the − 13( −2 ) y-coordinate of the point of + 15 tangency. = 21 Use ∴ y − 21 = 11( x the write Exercise Find point (−2, 21) and m = 11 to + 2) the equation of the tangent line. 7G the equations of the tangent and normal lines to the graph 2 of f (x) lines 2 = by Find x – 4x at the point (3, –3). Graph the function and the hand. the equation for the tangent line to the cur ve at the given point. 2 f a (x) = x + 2x + 1 at (–3, 4) b f (x ) = d f (x ) = 2 x + 4 at x = 1 2 x 8 + 6 4 f c (x ) = at (3, 5) x + at x 3 Find at the the equation given x = 1 x for the normal line to the cur ve point. 4 1 2 a f (x) = 2x – x – 3 at (2, 3) f b (x ) = at x = –1 2 x x 4 3 2 c f (x) = (2x +1) at (2, 25) f d (x ) = 2 x − at x = 1 2 x Exam-Style 4 Find the Questions equations for all the ver tical normal lines to the graph of 3 f 5 (x) The = x – 3x gradient of the tangent line to the graph of 2 f (x) = 2x + kx – 3 at x = –1 is 1. Find the value of k. Chapter . Y ou More can use rules a GDC for to derivatives evaluate a derivative of a function 1 3 at a given value. We know that the derivative of f (x ) = x − 3x 4 3 3 2 2 is f ′( x ) = x and − 3 so f ′( 4 ) = (4 ) to Click Choose and the display the enter value − 3 = 9 4 4 the templates. first-derivative the of function, template variable and x GDC help on CD: demonstrations Plus and GDCs Since line the to calculator is approximate using the a value Y ou can it will graph not the always function are of derivative by pressing be the CD. nd the derivative exact. and menu TI-84 the at a of x, specic use the value context find menu its on the FX-9860GII secant T o derivative, Casio Alternative for : show of its the point to coordinates, dy and Analyze Graph | 5: and point Y ou can on the the look at function x-coordinate. the and graphs its and a table derivative. To of values graph f and f time the first-derivative template to write the and derivatives value entering the Limits a of will x. be Y ou no space can save to time function. by there ′, enter use the graph. This for edit choosing dx the then f 1(x) equation. instead of re-typing x Investigation – the derivatives of e and x Use 1 a GDC Examine to the functions to graph f (x) graphs make = and a x e and the ln x the table conjecture of derivative values about the of for f(x) = e the derivative of x f(x) = Use 2 e a GDC Examine make a to the graph f (x) graphs conjecture = and ln x the about and table the the of derivative values derivative of for f (x) of f (x) the = = ln x functions to ln x x ➔ Derivative of e x If f (x) = e x , then f ′(x) = x e Recall y = that ln x are y = e and inverses. ln x e ➔ Derivative of = x ln x x ln e 1 If f (x) = ln x, then f ′( x ) = x = x Example Find the derivative of each x f (x) a = The function. 2 3e f (x) b = x letter e ln x c f (x) = as ln e the base exponential Answers Use x f (x) = the constant multiple rule and 3e x x f ′(x) = fact x 3 · e = that the derivative of e (x) = x + is e Find the derivative of each ter m. 2 1 f ′(x) = 2x 2x of = the e , in function honor Swiss mathematician 3e ln x the (x) x 2 f b ofthe x f a isused 3x + Leonhard Euler (1707–83). + 1 Use that fact that the derivative of or + 1 x x ln x is x 3x c f (x) f ′(x) = ln e = = 3x Use 3 the inverses Then Exercise Find the fact to find the of each (x) = 3 f (x) = 5 f (x) = functions are first. derivative. function. x f the 7H derivative 1 that simplify 4 ln x 2 f (x) = e 4 f (x) = 6 f (x) = x + 4 2 3 x ln e ln 4 x + ln x e x 2e + 3x x + ln x 5e + 1 x + 4 ln e Chapter Write an equation for each line in questions 7–10. How x The 7 line tangent to the cur ve f (x) = are exponential functions 4e – 7 at x = used in ln 3 determining the 2 x 8 The normal line 9 The line tangent 10 The line normal to the f cur ve (x ) = ln ( e ) at the point concentration (–3, 9) drug to the cur ve f (x) = ln x at x 2 Find in the exact questions value to to value and 11 check your the of 12 cur ve the and f (x) = derivative then use a e in a a patient’ s body? ln x 2x at = of + the e – given GDC to 3 at x value find an = 2 of x approximate work. x 11 Find f ′(3) if f (x) = 12 Find f ′(8) if f (x) = 2e − 5 3 Investigation + x – ln x the derivative two steps 1–4 let u(x) = x the product of functions 4 For of 7 , v(x) = x and f(x) = u(x)·v(x) n 1 The function 2 F ind f can written as f(x) = x . F ind n The f ′(x). 3 F ind u ′(x) 4 F ind u ′(x) · v ′(x) 5 Is f ′(x) 6 Using ll be in and the the the v ′(x). of same three as If u ′(x) · v ′(x)? derivatives blanks derivative functions below to found make a in steps true 2 and 3, mathematical the f (x) Is a is two = of the the sum sum of of the two derivatives functions. u(x) + similar v(x) rule two functions? The conjecture then true f ′(x) for = u′(x) the + v ′(x). product of statement. 4 f ′( x ) = x 7 ⋅ _______ + x ⋅ _______ = is 7 Complete the known f(x) = as the the investigation product rule. Many conjecture. proofs If in _______ u (x) · v (x) then f ′ ( x ) = ____ ⋅ ____ + are straightforward, but the ____ ⋅ ____ proof of this rule uses a creative step. 2 8 Use help the function conrm f(x) your = (3x + conjecture 1)(x from – 1) step to 7. reject or Y ou an can research example complete Limits and derivatives of the a the proof clever proof. and step nd needed to 4 For functions like f (x) = 7 x · x 2 and f (x) = (3x + 1)(x − 1) you can Product rewrite the function But other and use the power as (x) r ule to take the The for functions such f = (3x + 1)(ln x) you would derivative r ule like the one developed in the conjecture to find the following quotient ➔ of The r ules two are used to find the derivative of the product or the the functions. product f (x) = then f ′(x) = u(x) · v ′(x) + rst factor quotient plus factor times derivative If f then f ′( x ) the factor . is rule derivative quotient v ( x ) ⋅ u ′( x ) − u ( x ) ⋅ v ′( x ) ( x ) = of the v(x) · u′(x) rule u( x ) times the factor The The of second Quotient ➔ the factors second the rule u(x) · v(x) two derivative rst If of derivative. is The of need product a rule derivative. the of of two the factors denominator = 2 v(x ) [v ( x times )] of the the minus times of the the the all by derivative numerator numerator derivative denominator , divided denominator Example Find the of each (x) = c f (x) = squared. function. 4 f the derivative a by (3x 5x + 1)(ln x) b f (x) = d f (x) = (x + 3 x 2 3 + 3x + 6)(2x − 1) + 2 x x + 1 2e 3 Answers First factor Second factor f a f (x ) = (3 x + 1) (x) = u(x) · v(x), where u(x) = 3x + 1 (ln x ) is the first factor and v(x) = ln x is the second factor. Derivative of First second Second Derivative Apply the product rule. factor factor ⎛ f ′( x ) = (3 x 1 + 1) ⋅ + ⎜ ⎝ 3 + (ln x ) ⋅ (3) x 3x u(x) f (x) = u(x) u(x) = x v ′(x) + v(x) u ′(x) + 1 + 3x ln x x factor 4 b = or = ′(x) ⎠ x (x ) f ⎟ + 3 ln x First f first 1 = of ⎞ Second factor 3 (x + 3x + 6) (2 x − 1) v(x), 4 First where 3 + 3x + 6 is the first factor Derivative factor of 4 f ′( x ) = second and + 3x + 6) ⋅ (2) Apply = f of factor 2x – 1 is − 1) ⋅ ( 4 x 4 (2 x the second factor. 4 ′(x) = u(x) v ′(x) + v(x) u ′(x). first 2 + 9x ) + 12 ) + 3 − 4 x Expand 3 + 18 x 4 = 10 x rule. 3 + 6x (8 x product 3 + (2 x the Derivative Second = v(x) 3 (x 3 + 20 x the brackets. 2 − 9x ) 2 − 9x + 12 Simplify. { Continued on next Chapter page u( x ) 5x + 3 f(x) f c (x) = , where u(x) = 5x + 3 is the numerator = 2 v(x ) x + 1 2 f ′(x) and = v(x) Derivative of Apply Denominator numerator = x + 1 is the denominator. Derivative of Numerator the quotient rule. denominator (5 x (2 x ) 2 v ( x ) ⋅ u ′( x ) − u ( x ) ⋅ v ′( x ) (x + 1) ⋅ (5) − + 3) f 2 ′(x) = 2 2 (x + 1) [v ( x )] Denominator 2 squared 2 (5 x + 5 ) − (10 x + 6x ) Expand the numerator so that you can combine like = 2 2 (x + 1) ter ms. Do not expand the denominator. 2 −5 x − 6x + 5 Simplify. = 2 2 + 1) (x x + 2 u( x ) f d (x) = f x 2e (x) = , where u(x) = x + 2 is the numerator and 3 v(x ) f x ′(x) = v(x) numerator 2e – 3 is the denominator. Derivative of Derivative of Denominator = Numerator denominator Apply x the quotient rule. x (2e 3) ⋅ (1) − (x + 2) (2e ) 2 v ( x ) ⋅ u ′( x ) − u ( x ) ⋅ v ′( x ) x ( 2e 3 ) f ′(x) = 2 [v ( x )] Denomi nator x squared x ( 2e − 3) − ( 2 xe x + 4e ) Expand the numerator so that you can combine = 2 x ter ms. ( 2e 3 x Do not expand ) x −2 xe − 2e − 3 = 2 x ( 2e 3 ) Simplify. Exercise Find the 7I derivative of each function in questions 1 to 8. 2 x 3 1 f (x) = x 2 f (x) = (2x 4 f (x) = ln x 3 f 2 + x 2 + x)(x + 4 x (x) = e ln x x x 5 f x 2 x + 4 e (x) = f 6 (x) = x e + 1 2 2 x 7 f (x) = x 3 e (5x + 4x) f 8 (x) = 3 x Exam-Style + 1 Questions x 9 The function Find 10 (x) the = equations x + 1 x 1 that = Limits (x) xe has a horizontal tangent line at x k Write f f and are derivatives for the parallel tangent to the lines line x to + the 2y = graph 10 of = k 1) the denominator. like The product quotients. before do is quotient r ules sometimes are more not needed convenient to all products the and function the derivative. If it is more convenient to rewrite the function first, so. 3x 2 a for rewrite differentiating. Example Find and It f (x ) = x (4 x − 2x ) b f (x ) + 4 = 2 x 2 2 3x 9 c f (x ) = d f (x ) + 2x + 1 = 2 3 4 x x Answers 2 f a (x ) = x (4 x − 2x ) 1 2 2 = x (4 x 3 2 = Rewrite − 2x ) 5 Use the 4 ⋅ −1 3 2 x − 2 ⋅ x 2 3 1 2 2 = 10 x 3x f (x ) − 3x + constant multiple and 2 power b exponents 3 −1 2 = rational − 2x 5 ′( x ) expand. 2 4 x 5 f using and rules to and simplify. Use the find the derivative 4 = 2 x 2 2 (x f ′( x ) − 2 ) ⋅ (3 ) − (3 x + 4 ) ⋅ (2 x ) = quotient rule. 2 2 ( x 2 2 ) 2 (3 x − 6 ) − (6 x + 8x ) = 2 2 ( x 2 ) 2 −3 x − 8x − 6 = 2 2 ( x 2 ) 4 9 3 c f (x ) = = 3 9x Rewrite using Rewrite by rational exponents. 4 x 4 − 4 −1 3 f ′( x ) = 9 ⋅ − x 3 7 12 3 = −12 x = − 7 3 x 2 3x f d (x ) + 2x + 1 = 2 x 2 3x = 2x + 1 2 2 x 2 x ′( x ) = 3 + 2x + 0 − 2x −2 = then use rational exponents. x −3 − 2x 2 −2 x − 2 or − 2 x and −2 −2 f ter ms x −1 = separating + 3 x 3 x Chapter We have been using the ‘prime’ notation, f dy We can use Leibniz ′(x), to denote derivatives. d notation, [ f or ( x )] and we can also use dx dx dy variables other than x and y. The is notation read as ‘the dx derivative of y with respect to x’, or ‘d y by d x’, or simply derivative of f ‘d y d x’. d The [ f notation ( x )] is read as ‘the with dx respect to x’. Example [ Gottfried Leibniz d [ (ln Find a x )(7 x 2 2) ] s (t ) If b = (4t − 1) German ds 2 , Wilhelm (1646–1716), a mathematician, find debated dx with Isaac dt Newton over who dA 2 If c A πr = , was find dr the develop r =3 It is rst to calculus. widely believed Answers that d Use [ (ln x )(7 x the product rule to find the Leibniz Newton 2) ] a derivative dx of (ln x)(7x − 2) developed with about ⎛ = (ln x )(7 ) + (7 x 1 ⎝ x ln + 7x respect ⎞ to x. − 2) ⎜ 7x ⎟ x ⎠ − 2 = x 2 s (t ) b = 2 (4t Expand − 1) 4 = 16t 2 − 8t find the and use the derivative power of s rule with to respect + 1 to t. ds 3 = 64 t − 16t dt 2 A c 2 r Find the respect dA derivative to of πr with r. 2 r dr The dA bar tells you to evaluate the 2 (3) derivative dr when r = 3 r 3 6 Exercise 7J Differentiate convenient each to function rewrite the in questions function first, 1 to do 12. If it is so. 3 2x 1 f (x ) 5x 2 = 2 f (x ) = 4 f (x ) = (x x x f (x ) = 2e 2e 2 (x ) 2 x 2 (x ) = e x 4 3 ln 5 x + 6 f (x ) = x 5 4 x Limits and derivatives e 2 − 5 )( x 3 3 and independently + 5) more the calculus same at time. 2 x f 7 (x ) = 2 x + 1 8 f (x ) = 3x 9 f (x ) = ln x 2 x − 2x + 1 x 2 10 f (x ) = 11 f (x ) = x (x + 1) x 2 x − 2x + 1 3 12 f (x ) = 2 (x − 3 x )(2 x Exam-Style 13 Write the f (x ) 14 Write the + 5) Questions equation x of + 3x = of the line normal to the graph x xe − e at equation x of = the 1 tangent line to the graph of 3 f (x ) = x ln x at x = 1 dc 2 15 If c (n ) = −4 .5n + 3 .5n − 2, find dn 4 dA 3 16 If A = πr , find 3 dr dv 2 17 v (t ) If = 2t − t + 1, find dt t =2 Exam-Style Question d t t ⎡ (e 18 )( t + 3) ⎤ ⎣ can be written as e (t + k ). Find k ⎦ dt . The chain rule and higher order The symbol is used ° to show a composite derivatives 3 function. The power r ule alone will not give the correct derivative If u( x ) = x for and v ( x) = 2 − x, then 3 f (x ) = rather (2 − a x ) . power This of is because another the function function v ( x ) = is 2 − not x. a The power of function x, f but is a f ( x) = (u = u(v ( x )) = u v )( x ) 3 composite v(x ) = 2 − function, (u v )( x ) or u ( v ( x )), where u( x ) = x and (2 − x ) 3 x = (2 − x ) Chapter Investigation – finding the derivative composite of a function 3 Let 1 f (x) = (2 − x) 3 a Expand b Y ou f (x) derivative = of (2 − x) Differentiate each term to nd the f 3 can also nd the derivative of f (x) = (2 − x) by applying 3 the power Compare rule the to (2 − x) following and to multiplying your answer in by another step 1 factor . and nd the 2 If u(x) = x and 2 missing factor : f ′(x) = 3(2 − x) ._____ v(x) = 2x + 1, then 2 Repeat 2 the process for f (x) = (2x + 1) f ( x) a Expand b Apply f and nd the = u(v ( x )) = u(2 x = (2x derivative. + 1) 2 f ′(x) the = power 2(2x + rule to (2x + 1) to the a Expand b Apply process f the missing factor : 2 and for nd f (x) the = (3x 2 + 1) derivative. 2 If 2 the power rule to (3x u(x) = 2(3x + 1) to nd the missing factor : Make a x and 2 = 3x + 1, then 1)._____ f ( x) 4 = 2 + v(x) f ′(x) + 1) 1)._____ 2 Repeat 3 nd conjecture about nding the derivative of = u(v ( x )) = u(3 x a 2 composite + 1) function. 2 4 Verify 5 To find the ➔ the chain The If that f your conjecture derivative of a works for composite f (x) = (x function 2 + x we = 3 2 (3 x + 1) ) use r ule. chain (x) = rule Chain u(v(x)) then f ′(x) = The u ′(v(x)) · v′(x) rule derivative composite is ➔ The chain r ule can also be written the dy y = f (u), u = g (x) and y = f (g(x)), dy = then derivative outside du du respect function function the function is in the form f (x) = u(x) and v(x), then find the derivative of derivative respect (x ) = 2 6 4 (5 x + 2) f b (x ) = 4 x x + 1 f c (x ) = e Answers 3 a f 6 ( x ) = 4(5 x + 2) 6 u( x ) = 4 x u is the outside function. 3 v ( x ) = 5x + 2 v 3 f ′( x ) = 24(5 x 5 is the ( 15 x Apply Derivative with chain rule. Derivative of of function function. ) outside inside 2 + 2) inside with respect function respect to x to inside function 2 = 360 x 3 (5 x 5 + 2) Simplify. { Limits and derivatives of function f. 2 3 f remains multiplied the by the u(v (x)) inside a the (inside same), Identify to dx inside Each of function ⋅ with dx Example a as: the If of function Continued on next page to x with 2 f b (x ) = 4x Rewrite +1 using rational exponents. 1 2 2 = (4 x + 1) 1 2 u(x ) = x u is the outside function. 2 v (x ) = 4x v +1 is the inside function. 1 1 2 f ′( x ) = 2 (4 x + 1) Apply (8 x ) the chain rule. 2 Derivative of function with Derivative of outside respect inside function to inside functi ion respect 4 x with to x 4 x = or Simplify. 1 2 2 (4 x 4 x 2 + 1 + 1) 2 x f c (x ) = e 2 ( x ) = e x u( x ) = e u is the outside function. 2 v(x ) = v x is the inside function. 2 ( f ′( x ) = x ) e the chain rule. Derivative outside function with Apply (2 x ) Derivative of respect of to inside function inside function respect with to x 2 x = 2 xe Exercise Each 7K function Identify Simplify. u(x) is in and the v(x), 4 f 1 (x ) = form then f (x ) find = the u ( v ( x )) derivative 5 (3 x f (x ) = ln(3 x 2 f (x ) = 4 f (x ) = f (x ) 6 f (x ) = 8 f (x ) = 10 f (x ) = e 3 4 (2 x + 3x + 1) 3 ) 2x + 3 4 x 5 f. 2 + 2x ) 5 3 of 3 = e (ln x ) 2 f (x ) = (9 x 2 4 3 7 + 2) 2x + 3 3 3 9 f Y ou (x ) = 5( x can find rewriting Maria the Agnesi published calculus a of 4 4 x + 3x ) the derivative function into (1718–99), text both on a an calculus Isaac of some form Italian that Newton functions where can efficiently apply the chain by rule. mathematician, included and you more the Gottfried methods of Leibniz. 3 a Maria also studied cur ves of the form y whose = 2 x graphs came to be known as witches of 2 + a Agnesi. The function 1 f ( x) in = Example 13 is an example of such a graph. 2 x + 1 Chapter Example 1 Use the chain r ule to find the derivative of f (x ) = 2 x + 1 Answer 1 f (x ) = Rewrite 2 x 2 ′( x ) rational exponents. 1 + 1) = (x = −1( x 2 f using + 1 2 + 1) ⋅ 2x Apply the chain rule. 2x = − 2 2 (x For some product Simplify. + 1) functions or the quotient Example chain r ule, or r ule the must chain be r ule combined may need with to be 4 f (x ) repeated. 2 a the = x 1 − 2 (3 x x f b (x ) = x ⎛ 1) e f c (x ) = ⎞ ln ⎜ ⎝ ⎟ 2 + 1 x ⎠ Answers 1 2 a f (x ) = x 1 − 2 x = x (1 − 2 x Rewrite ) using rational exponents. 1 1 2 f ′( x ) = x (1 − x 2 ) ( −2 x ) 2 First factor Derivative of using second chain Apply chain the product rule to find rule, the using the derivative of factor the rule second factor. 1 2 (1 + 2 x ) 1 Derivative of Second factor first factor 1 2 x 2 + (1 = x Simplify. 2 ) 1 2 (1 2 x ) 1 1 2 2 x (1 2 + (1 = x x 2 ) Find 2 ) 2 (1 2 2 x ) (1 2 x a common denominator. 1 1 x 2 ) 2 + (1 x ) = 1 2 (1 x 2 ) 2 1 2 2x 1 = 2x Simplify. or 1 2 2 (1 1 2 x x ) 4 2 (3 x b f (x ) = e u( x ) = e 1) The are x outside shown. and inside Note the functions inside function 4 v(x) = 2(3x − 1) is the composition 4 v(x ) = 2 (3 x − 1) 4 of 2x and 3x − 1. 4 2(3 x f ′( x ) = 1) 3 e 8(3 x Derivative of 1) (3) chain rule to f and apply the outside function inside function respe ect the the Derivative of with Apply to the res pect to it again when finding the derivative with x of inside function the inside function. 4 2(3 x 3 = 24(3 x 1) 1) e { Limits and derivatives Continued on next page x ⎛ f c (x ) = ⎞ ln ⎜ ⎟ 2 + 1 x ⎝ ⎠ 2 1 (x + 1) ⋅ 1 x ⋅ (2 x ) Apply f ′( x ) the chain rule and use the = 2 x 2 ( 2 x x + 1 ) quotient rule to find the derivative + 1 Derivative of Derivative of the of the the inside function. inside function outside function with with respect respect x to the inside function 2 2 x + 1 2 x + 1 2x = Simplify. 2 2 x ( x + 1 ) 2 1 x = 2 x (x Exercise Find the + 1) 7L derivative of 2 1 f (x ) = f (x ) = x each function in questions 4 (2 x 2 − 3) 2 f (x ) x = x (x ) = + 3 2x 2 x 5 f (x ) = f (x ) = + 1 2 x e 3 + e f 6 (x ) = ln(1 − 2 x ln(ln x ) f 8 (x ) = x x e 1 9 f (x ) ) 2 2 7 10. x f 4 2 x to e 4 3 1 + e 4 = 10 f (x ) = 2 x x + 3 2 x − 3x Exam-Style − 2 Questions 2 x 11 12 For the the a Find c Hence Find the f f cur ve (x ) ′(x). Find b find the 2 x = e equation x-coordinate of the of f ′(2). the tangent point(s) on line the to f graph when x = 2 of 3 f (x ) = x ln x where the tangent line is horizontal. 1 13 Let f (x ) = , g(x ) = 1 − 2x and h( x ) = ( f g )( x ) 3 x Find h (x) and show that the gradient of h (x) is always positive. x f (x) g (x) f ′(x) g ′(x) 3 1 4 −3 2 4 2 −1 3 4 In at the x = table 3 and above, x = 4 the are values of f and g and their derivatives given. a Find the gradient of b Find the gradient of ( f g )( x ) when x = 3 1 when x = 4 2 [ g ( x )] Chapter Higher order derivatives The second derivative is the derivative dy The derivative f ′(x) or is called the first of derivative the dx d as of y with respect to x. We are sometimes interested rst ⎢ in dx derivative. Writing this ⎡ dy ⎤ helps ⎥ you see where the ⎣ dx ⎦ 2 the gradient of the first derivative. This is known as d the y comes notation from. 2 dx second derivative written as of y with respect to x and can be 2 d f ″(x) y or . The third derivative of y with 2 dx The 3 d respect to x is written as f ″′(x) ‘prime’ notation is not ver y useful y or . The second and for derivatives of order higher than 3 dx three. third derivatives are examples of higher order derivatives For those derivatives (x). For example, instead (4) f ″′′(x) Find b If we 4 a the first three derivatives of f (x ) = 2 x + 3x + x 3 d ′( x ) = x 2 x 2 f + 4 , x find f ′′( x ) . If c y = 4e , find 3 dx 2 d 2 d s (t ) If = −16t + 16t + 32, x =1 s find 2 dt Answers 4 a f 2 (x ) = x + 3x ′( x ) = 4 x + The x f 3 f + 6x first ′ ( x ), three f ′′ ( x ) derivatives and f are ′′ ( x ) + 1 2 f ′′( x ) f ′′′( x ) f ′( x ) = 12 x = + 6 24 x 2 b = x Note + 4 2 = (x that given, 1 so the you first derivative only was dif ferentiate once 2 + 4) to get the second derivative. 1 1 2 f ′′( x ) = (x 2 + 4) (2 x ) 2 x = 2 x + 4 2 x = y c 4e Find the first three derivatives using dy 2 x = 4e = 8e 2 x ⋅ 2 = 8e the chain rule. dx 2 y d 2 x 2 x ⋅ 2 = 16e 2 dx 3 y d 2 x 16e = 2 x ⋅ 2 = 32e = 32e 3 dx 3 d Then evaluate when x the third derivative y 2 (1) = 32e 2 3 = 1 dx x =1 2 d s (t ) = −16t + 16t + 32 = −32t + 16 dt 2 d s = −32 2 dt Find the first derivative ds Limits and derivatives of and s then with write (n) f Example we the respect second to t. write f (x). of writing Exercise 7M 3 2 1 Find 2 If 3 If the second derivative 5 f (x ) f of (x ) = 4 x 4 = 3x + x + 2x + 1 , find f ′′′( x ) 2 d C 3n C (n ) = , (3 + 2 n )e find 2 dn 3 dy d 4 = If 4 , y find 3 dx x dx 6 4 d d y y 3 = If 5 ln( 4 x ) , find 6 4 dx dx dR 1 2 If 6 R (t ) = t ), ln( t find dt 2 t = −1 Exam-Style Questions 3 What 7 for n is ≥ tr ue about the nth derivative of y = 2 + 3x + 2x + 4, 4? x Find 8 x the first four derivatives y of = e x + e then write a n d generalization for y finding of this function. n dx 1 Find 9 the first four derivatives y of = then write a generalization x n d for y finding of this function. n dx 5 10 Find . The the Rates of section we of diver the in the the variable will motion of slope change gives one Example A of derivative change and gradient slope with of the and of a function motion function. respect to It f in also another (x ) a 2 = 3 x line gives variable. the In rate of this study average and instantaneous rates of change a line jumps diver from above a platform water level at at time time t t = is 0 seconds. given The distance by 2 s (t ) a = −4.9 t Find the + 4 .9 t + 10 , average where s veloci ty is of in metres. the diver over the given time inter vals. i b [1, 2] Find the ii [1.5, 1] instantaneous iii [1.1, 1] veloci ty of iv the [1.01, 1] diver { at t = 1 second. Continued on next page Chapter The Answers of a Average velocity is average change in rate s, or the average change of velocity, is the (metres) distance −1 The change in units for velocity are slope m s of a secant line: (seconds) time s(t + h) − s(t ) s(t + h) − s(t ) = (t s (2) + h) − t h s (1) 1 i = 2 −9 8 ms The Find 1 the slopes of the secant instantaneous lines rate s (t ) s (t 2 s (1.5 ) on 1 = ii −7 35 m s t 5 each inter val. Use a or the change velocity, slope GDC to evaluate the of a v (t ) s (1) 1 = 1 1 −5 s (1.01) s (1) 1 = 1 b 01 = s ′( t ) 949 m s 1 Instantaneous v (t) −4 velocity s ′(t) = −9.8t −9.8 + 4.9 = Find the s = at t slope of the tangent line to 1 Note that the slopes of + 4 .9 the secant lines in part a approach the slope of 1 s ′(1) the −4.9 m s = tangent line in part b Example During one month, the temperature of the water in a pond is modeled t 3 by the function measured a Find 15 b in the days Find degrees average of the C (t ) the rate = 20 + 9 te , where t is measured in days and C is Celsius. rate of change in temperature in the first month. of change in temperature on day 15. Find the slopes Answers a Average rate C (15 ) of change C (0 ) = line ≈ 15 0 on the of the inter val secant [0, 15]. The 0606 °C/day change in temperature 0 units for are change in time °C b Instantaneous rate of change: t ⎛ = 9t ⎜ 1 ⎞ − e ⎟ + e ⋅ 9 3 ⎠ t t − − 3 −3te 3 + 9e −5 C ′(15) = − 3 ⋅ 15e −5 + 9e 5 = − 36e ≈ − 0 On is day degrees 15 Limits and 243 °C/day the dropping at Find C − 3 ⋅ − ⎝ = / day the slope t 3 C ′( t ) temperature a Celsius rate per derivatives of 0.243 day . = at t = 15. of the tangent line to + h) lim h→0 39 m s 1 iv tangent line: slopes. s(t s (1.1) s, the 1 1 iii of is t 2 1 of ) 1 s (1) − s(t ) = h s (t ) Exercise Use a 7N GDC to Exam-Style 1 A ball is ground help function values. Question thrown t evaluate ver tically seconds after it upwards. is thrown Its is height in modeled metres by the above the function 2 h (t ) = −4 .9 t Find the height b Find the average t seconds c = 0 Find the the ball The + 1 .4 of to the rate t = ball of 2 t what amount of = 1 when change rate second, these water t = of 0 seconds the height and of when the ball t = 2 seconds. from seconds. instantaneous when Explain 2 + 19 .6 t a values in a of t change = tell tank 2 of the seconds you about after t height and the minutes t = 3 of seconds. motion is of the modeled ball. by 2 t ⎛ the function V ( t ) = 4000 ⎞ , 1− ⎜ Answer the following Find the amount a when b Find tank t = the 20 from c Find tank d The that t the rate t your = 0 number t is measured in litres. in whole the tank number. when t = 0 minutes and = of 0 = the change minutes of to t the = amount 20 of minutes. water in Explain the the answer. 20 rate minutes. amount minutes of nearest water instantaneous when Show from 3 the when of of V ⎠ minutes. average meaning to where ⎟ 60 ⎝ to bacteria of change Explain water t=40 in of a in of the the the amount meaning tank is of never of water your in the answer. increasing minutes. science experiment on day t is 0.25t modeled a Find over b Find by the the Find The rate 0 to of 10 instantaneous at the cost 100e average the bacteria 4 = inter val bacteria c P (t) any time (in day 10. dollars) days of the the number of bacteria experiment. rate of change of the number of rate of change of the number of Explain of of t. instantaneous on change the producing meaning n units of of a your answer. product is modeled 2 by the function a Find the when b average the = 0.05n rate production of = 105 units and when n = 100 units to = Find the any Find when n 101 instantaneous number the n of = 100 units. + of changes the 5000 C with from n production respect = level 100 to n units changes to from units. rate units instantaneous +10n change level n for c C (n) of change of C with respect to n of change of C with respect to n n. rate Explain the meaning of your answer. Chapter Motion If an in object a line moves along a straight line, its position Y ou from an origin at any time t can be modeled by line function , displacement s(t). The can use a horizontal or ver tical a to model motion in a line. function For s(t) > 0, the object is to the right 2 s(t) = + −4.9t 4.9t + 10 from Example 16 is an example of of a displacement diver The is position origin diving ➔ the is at when water platform The function. 10 t The = level, metres instantaneous 0, so ini tial or the above rate of s(0) posi tion = diver water 10 is of the metres. initially the s(t) < origin on a origin 0, or position or the below is above object the origin. s (t = change + h) − s of displacement is For the v(t) = For s ′( t ) is is moves after by in a s (t) straight leaving = 2t a to object the right v(t) < 0, the down object or to left. v(t) at = 0, the object rest. ini tial veloci ty v(0). line fixed with point. a displacement The of displacement s metres function 2 − 21t + 60t + 3, for t ≥ 0. This a Find the velocity b Find the initial of the par ticle at any time is an area position and initial velocity of the Find when the par ticle is at d Find when the par ticle is moving kinematics, rest. which left and when the par ticle is a about the is motion moving known par ticle. as c of t mathematics Draw the 3 e 0, moving The given initial up. For seconds > moving the is the h is t The For of (t ) lim h →0 particle left level. or A origin. the s(0). is Example the to function , veloci ty (t ) is of objects. right. motion diagram for the par ticle. Answers a v (t ) = s ′( t ) v (t ) = 6t s (0 ) = 2( 0 ) Velocity is the derivative of displacement. 2 − 42 t + 60, 3 b t ≥ 0 2 − 21( 0 ) The + 60 ( 0 ) + 3 = 3 m when 2 v (0) = 6(0) 6t − 42t t = position is the displacement 0. 1 − 42(0) + 60 = 60 ms 2 c initial + 60 = The initial velocity The par ticle is at is rest the velocity when when velocity is t = 0. 0. 0 Set the velocity function equal to 0 and solve for t. 2 6( t − 7t 6( t + 10 ) − 2 )( t − 5) t The par ticle is = 0 = 0 = 2, at 5 rest at 2 seconds and 5 seconds. { Limits and derivatives Continued on next page signs d of + v Make + t 0 The 2 par ticle (5, ∞) moving right because for (2, 5) 3 e s (2) = v (t) for > (0, 2) − 21( 2 ) 3 t = = seconds 0. The par ticle because = 0 t = + 60 (5 ) + 3 v (t) < the (0 , 2) t = 1 v(1) = 6(1 − 2)(1 − 5) = (+)( − )( − ) = + (2 , 5) t = 3 v(3) = 6(3 (+)(+)( − ) = 55 28 the find diagram. − 2)(3 the sign − 5) = of Choose a v(t). − t = v(6) 6 = 6(6 − 2)(6 − 5) = (+)(+)(+) = + the displacement or position of the par ticle m the par ticle changes direction. = 28 m = Use these plot the positions motion. and the Although initial the position motion to is 2 actually on the line, we draw it above the line. on a line with displacement function 2 − Find a and 55 moves 3 t inter val 7O par ticle = each is s s (t) on values 0. 5 t A rest the in Find + 60 ( 2 ) + 3 − 21(5 ) 0 3 1 at Put 2 2 (5 ) Exercise is velocity. value when s (5) par ticle for and 2 2( 2 ) diagram when (5, ∞) left sign 5 is seconds moving a 6t the + 9t centimetres initial position for and t ≥ the 0 seconds. initial velocity for the par ticle. b Find when c Draw a A ball is par ticle motion Exam-Style 2 the is diagram at rest. for the par ticle. Question thrown ver tically upwards. The height of the ball in feet, 2 t seconds t ≥ 0 a Find b Show is c after it is released, is given by s (t) = −16t + 40t + 4 for seconds. 20 the that is a of the Solve ii height of of the the ball. ball after 2 seconds second time when the height of the ball is feet. Write i the height feet. There 20 initial down ball the an is equation 20 that t must satisfy when the height feet. equation algebraically . ds d i Find ii Find the iii Find when iv Find the dt 3 A par ticle initial velocity the velocity maximum moves along a of of height line the the of with ball. ball the is 0. ball. displacement function t s (t ) = , where s is in metres 1 t and t is in seconds. t e a Show that (t ) = t e b Hence find when the par ticle is at rest. Chapter ➔ The instantaneous rate of change of v (t function , acceleration a (t ) = the velocity + h) − v = v ′( t ) a(t) > 0 the velocity of the object is increasing. For a(t) < 0 the velocity of the object is decreasing. For a(t) = 0 the velocity is the = s ′′( t ) h For For the (t ) lim h →0 Example is constant. displacement 3 function from Example 18, 2 s(t) = we found 2t − 21t + 60t + 3, with s in metres and t ≥ 0 seconds, 2 a b that v (t) Find the t seconds = 1 to Find the seconds. 3 6t average t = = t − 42t + 60. acceleration = 4 of the par ticle from seconds. instantaneous Explain acceleration the meaning of of the your par ticle at answer. Answers a Average acceleration is 2 1 change in change v (4 ) (m s velocity in The units for acceleration are m s ) (seconds) time v (1) Use 2 = 4 b Instantaneous a(t) a GDC to evaluate. −12 m s 1 = a (t ) = acceleration v′(t) v ′( t ) = 12t − 42 2 a (3 ) = This −6 m s means decreasing each 3 the 6 second velocity metres at per is Note second does time is seconds. Speed is the that not value of velocity . negative mean slowing velocity absolute a is an down. acceleration object It in means motion that the decreasing. Velocity tells us how fast an For object is moving and the direction in which it is moving. Speed more value’ us only how speeding and up fast or it is moving. slowing acceleration. Limits and derivatives down To determine you can if an compare object the in signs motion of on ‘absolute tells is velocity see Section Chapter 2.7. 18, Investigation – velocity, and 1 Copy and change complete of velocity. Velocity a and the acceleration speed tables. Speed is Recall the acceleration are that absolute both acceleration value of Velocity b positive. is the velocity. is positive and acceleration −2 Let acceleration Time be Velocity 2 2 m s Let acceleration Time Speed be Velocity −2 m s Speed −1 −1 (sec) (m s 0 −1 ) (m s 10 1 (sec) ) (m s 0 10 −1 ) (m s 10 1 12 ) 10 8 2 2 3 3 4 4 Velocity c and acceleration are both Velocity d is negative. is negative and acceleration positive. 2 −2 Let acceleration Time be −2 m s Velocity (sec) (m s −10 1 −12 (m s Time be Velocity 2 m s Speed −1 ) (sec) 10 (m s 0 −10 1 −8 −1 ) (m s ) 10 2 2 3 3 4 4 State acceleration −1 ) 0 Let Speed −1 2 is negative. whether the object is speeding up or slowing down. If a Velocity and b Velocity is acceleration are both the speed object positive and acceleration is Velocity and d Velocity is acceleration are both an is increasing , negative. the c of positive. object is speeding negative. up. negative and acceleration is positive. If 3 Complete the the speed object If a velocity and acceleration have the same sign then is an is decreasing , the the object of statements: object is slowing ___________________. down. If b velocity object When velocity motion When is is is acceleration have opposite signs then the ___________________. and speeding velocity motion and and slowing acceleration have the same have different sign, the object in up. acceleration signs, the object in down. Chapter Example For the displacement 3 function from Example 18, 2 s(t) = we found 2t − a Find 21t + 60t + 3, with s in metres and t ≥ 0 seconds, 2 that the whether t b = 3 v(t) = speed the 6t of − the par ticle 42t + 60 par ticle is and at speeding t a(t) = up 3 = 12t − seconds or 42 and slowing determine down when seconds. During 0 speeding ≤ t up ≤ 10 and seconds, when it is find the slowing inter vals when the par ticle is down. Answers 2 a v(3) = 6(3) − 42(3) + To 60 −1 = given −12 m s −1 speed = |−12| find = the 12 m s the speed time, find absolute of the the par ticle velocity and at a take value. −2 a(3) = The t = b < 42 is seconds = −6 m s speeding since v(t) up < 0 at and The t = par ticle 3 have 0. Compare and − par ticle 3 a(t) 12(3) the signs of velocity acceleration. Use since the the from 12t of v 0 of it, a 42 2 5 ≤ t in 3.5 par ticle in v (t) the < speeding 0 because > a (t) is inter val because and in 18. a sign diagram a(t) = 0 = ⇒ t 0 = 3.5 value on the inter val 10. a v (t) the > up a(1) a (t) < 0, (5, 10) v (t) > slowing (0, 2) 0 because and a (t) > 0 Limits and derivatives down a (t) < (3.5, 5) v (t) 0. = t = 12(1) < 0 (3.5, 10) a(4) seconds and inter val seconds value in each inter val: 1 − 42 = −30 = 6 (−) seconds 0. particle the and inter val and in velocity 10 (2, 3.5) seconds The is inter val because and for ––––––––––++++++++++++++ 0 the diagram align this ≤ (0, 3.5) The acceleration sign. 10 Check t and at +++++––––––––+++++++++++ 0 signs sign when − Place t velocity same up a(t). Find signs speeding Example Below for is 0, = t = 12(4) 4 − 42 (+) Exercise Use 1 a A 7P GDC to par ticle help moves 4 s(t) = 2t − 6t Find at the Find A in of the par ticle a = the displacement function for the for t ≥ 0 velocity seconds. and acceleration of the at time t = 2 seconds and explain the answer. velocity par ticle moves + Write Find with and is acceleration speeding along a line up with and the equal zero. slowing Then find down. displacement function 2 −t 12t an par ticle b values. t your 3 s(t) line centimetres, time when when 2 a acceleration meaning c , expressions par ticle b along function 2 Write a evaluate 36t + expression at the − time 20, for in metres, the for velocity 0 ≤ and t ≤ 8 seconds. acceleration of the t initial position, velocity and acceleration for the par ticle. c Find when Then d Find find the inter vals when inter vals par ticle on changes which acceleration on which the is 0 direction the for par ticle par ticle 0 is for ≤ t ≤ 8 0 ≤ t travels up 8 right seconds. speeding ≤ and seconds. and Then left. find slowing down. Exam-Style 3 A diver QuestionS jumps from a platform at time t = 0 seconds. Look The distance of the diver above water level at time t is again at the diver given in Example 16. 2 by s (t) = a Write diver an at 4.9t + expression time Find when the c Find when velocity height A Show of the that par ticle 10, for where the s is in velocity metres. and acceleration of the t b d 4 + −4.9t diver hits the equals water. zero. Hence find the maximum diver. the moves diver is along a slowing line down with at t = 0.3 displacement seconds. function 1 2 s (t ) = t − ln( t + 1), t ≥ 0 where, s is in metres and t is in seconds. 4 a b i Write ii Hence i Write time ii an expression find an when for the expression the velocity par ticle for the is at of the par ticle at time t rest. acceleration of the par ticle at t Hence show that velocity is never decreasing. Chapter . The derivative and graphing Although named One of the most powerful uses of the derivative is the after Car tesian René the graphs of functions. In this section you how to connect f ′ and f ′′ to the graph of function in x on results an is increasing in interval an if on increase an an in increase y. inter val A in x if an function results in is a positive increase 1642–1727) decreasing decrease in rst his y use book Third x-axis used (English and an x-axis. is attributed negative linearum Enumeration Degree, a Newton y-axis with the coordinates. Enumeratio and mathematician, of ter tii Cur ves used and In both positive of an and coordinates. down increasing of or negative Write numbers Newton ordinis, Example he f Isaac A (French 1596–1650), will only see Descar tes was to mathematician, analyze plane the or inter vals on which the function is decreasing. y a y b 5 4 3 y c 5 3 4 2 3 1 2 2 x 1 1 1 –2 x 0 –5 –4 –3 –2 1 –1 2 3 4 5 x 0 –5 –4 –3 –2 1 –1 2 3 –3 –4 Answers y a Decreasing for x < 0 increase 5 Increasing for x > 0 in x 4 decrease increase 3 in y in y 2 increase 1 in x x 0 –5 b Increasing for all real –4 –3 –2 1 –1 numbers 2 4 3 5 y 5 4 3 increase in y 2 1 increase in x 0 –5 c Increasing for Decreasing x for < 0 0 < and x < 2 x > 2 –4 –3 –2 1 –1 x 2 3 y 3 2 1 x 1 –2 –3 –4 Limits and derivatives 2 2 ➔ When a function is decreasing, the tangent lines to the y cur ve have negative slope. When a function is increasing, 5 the tangent lines to the cur ve have positive slope. It follows 4 3 that: 2 If f ′(x) > 0 for all x in (a, b) then f is increasing on 1 (a, b). x 0 If f ′(x) < 0 for all x in (a, b) then f is decreasing –5 on –4 –3 –2 1 –1 2 4 3 5 (a, b). Example Use the derivative of f to find the inter vals on which f is increasing or A is decreasing. stationary a point point where 2 x 3 a f (x) = 4 2 2x − 3 3x − 12x b f (x ) = f (x) c = f ′(x) x = 0 2 x 1 A of cri tical f is a number point where Answers 3 f a (x ) = f ′(x) 2 2x − 3x = 0 or f ′(x) is − 12 x undened. 2 f ′( x ) = 6x − 6x − 12 Find the derivative Find the critical of f. 2 6x − 6x − 12 = 0 2 6( x setting − x − 2) = f − 2 )( x + 1) = x signs of = 2, Make is increasing since f a sign on ′(x) (−∞, −1) > f decreasing ′(x) < diagram for f ′(x). and can use on inter val notation to 0 describe is and 2 We f 0 − 1 –1 (2, ∞) to x. + x f for 0 + f' equal by 0 solving 6 (x ′(x) numbers (−1, 2) the inter vals. since 0 2 x f b (x ) 4 = 2 x 1 2 (x f ′( x ) 2 − 1)( 2 x ) − ( x − 4 )( 2 x ) Find the derivative Find the critical of f. = 2 2 (x 1) 6x = 2 2 (x f ′(x) = 0: 6x = 0 x = 0 1) f ′(x) undefined 2 (x when: setting f ′ equal numbers to 0 and by solving 2 − 1) = 0 for = 0 undefined. x, and by finding where f ′ is 2 x − 1 x = ±1 Make signs of f' – – + a Notice x –1 0 sign diagram for f ′. + that f and f ′ are not 1 defined circles at on x = the remember ±1. sign Use open diagram to this. { Continued on next page Chapter f is increasing (−1, 0) f is since on f ′(x) decreasing (1, ∞) since f (−∞, −1) > on ′(x) on 0. (0, 1) < We and cannot (−∞, 0) since and x 0. say = f is or not that f is increasing decreasing defined at on x = (0, ∞) −1 or 1. 3 f c (x ) = ′( x ) = x 2 f 3x 2 3x = Find the Find the = of + f' x is f ′ equal 0 and by solving x. a sign diagram for f ′ 0 increasing on (−∞, 0) Even and x (0, ∞). = the is though 0, we zero at Exercise f is defined cannot inter val x increasing Write numbers to + Make f f. 0 for signs critical of 0 setting x derivative include because = at 0, x so = at the f(x) 0 in gradient is not 0. 7Q down the inter vals on which f is increasing y 1 or decreasing. y 2 4 y 3 1 2 3 0 –2 2 x –1 –1 1 1 –2 –3 0 –4 –3 –2 x –1 1 2 3 x 4 –1 –1 –4 –2 –5 –3 –1 –6 –4 –2 In questions which f 4–9, use is increasing = x the or derivative f (x) 4 5 f f to find all inter vals on decreasing. 4 4 of (x) = x x + 2 x 3 2 − 2x 6 f (x ) Use = a a GDC graph of to the look at function 3 to x 3 7 f (x ) = 8 f (x) = x x e 9 f (x ) = 2 x x 1 y Exam-Style Question 4 10 The graph of the derivative of f is y shown. = f'(x) 3 Write down the inter vals on which f is 2 decreasing and increasing. 1 0 –3 –1 –1 –2 –4 Limits and derivatives x 4 verify your results. A function when the has a relative function maximum changes from (or point increasing local to maximum) decreasing. Note A function has a relative minimum point (or local not when the function changes from decreasing to that change relative minimum and of extrema a maximum points are called the then function. is number the point neither a minimum ➔ The first derivative test is used to locate relative extrema of f is defined at a critical number c does at a x = c, (c, f (c)) relative nor a f. relative If f ′(x) sign increasing. critical Relative if minimum) maximum. then: relative maximum If 1 f ′(x) changes from positive to negative at x = c, then f neither has a relative maximum point at (c, f a relative (c)). minimum relative If 2 f ′(x) changes from negative to positive at x = c, then f nor maximum relative minimum has a Example Use the relative minimum point at (c, f (c)). first derivative test to find the relative extrema for the functions in Example 22. 2 x 3 a f (x) = 4 2 2x − 3 3x − 12x f b (x ) = f c (x) = x 2 x 1 Answers 3 a f (x ) = 2x ′( x ) = 6x = 6( x 2 − 3x − 12 x 2 f signs of − 6x − 12 − 2 )( x + 1) + f' + Use –1 x Since x = f ′(x) f ′(x) −1 2 changes there is changes relative a from relative from minimum x 3 f ( −1) = 2 ( −1) positive = to maximum negative at to negative at x positive = at at −1. x = Locate Since 2 for there is (2) = = So for f ′ from relative changes extrema for f by looking ′ a Evaluate f at x = −1 and x = 2 to find − 12( −1) maximum and minimum values. 7 3 f diagram 22. the sign the = sign 2. 2 − 3( −1) the Example 2( 2 ) 2 − 3( 2 ) − 12( 2 ) −20 the relative minimum maximum point is point is (−1, 7) and the relative (2, −20). 2 x f (x ) 4 = b 2 x 1 6x f ′( x ) = 2 2 (x signs of 1) – f' – x –1 + 0 + 1 There Since f ′(x) changes from negative to positive at x = would not be relative extrema at 0 x = −1 f ′(x) and x = 1 even if the sign of 2 0 there is a relative minimum at x = 0. f (0 ) 4 = = 4 had changed, since f is undefined 2 0 1 at So the relative minimum point is x = −1 and x = 1. (0, 4). { Continued on next Chapter page 3 f c (x ) = ′( x ) = x 2 f signs of 3x + f' + x Note 0 that condition f has no relative the derivative does = 0. It sign Exercise In x = 0. 7R questions extrema at for 1 to each 8, use the first derivative test f (x) = to find the relative function. 2 1 3 2x − 4x − 3 2 f (x) = x 4 f (x) = x 6 f (x) = x 8 f (x ) − 12x − 2x − 5 5 4 3 3 f (x ) = x 3 5 f (x) = x (x + 2 2 3) x e 2 x 1 f 7 (x ) = − 2x + = 2 (x ➔ x + 1) If f ′′(x) > 0 for all x in If f ′′(x) < 0 for all x in The points on a graph inflexion points . A point ′′(x) and if f = 0 (a, b) then f is concave up (a, b) then f is concave down where point The f + 1 on ′′(x) graph the the concavity graph changes is concave of on on changes f is an (a, b). (a, b). are called inflexion sign. down for (−∞, 0). The tangent y lines 4 y = shown in red have decreasing gradients. This f(x) means that f ′ is decreasing , so its derivative f ′′ is negative. 0 x The –2 graph is concave up for (0, ∞). The tangent –2 lines shown in blue have increasing gradients. This –4 means that f ′ is increasing , so its derivative f ′′ is positive. The point concavity Limits and to = have 0 a is derivatives must also not a relative be not changes change ′(x) sufficient extrema at extrema x since f (0, 0) at x = is an 0. inexion point since f changes sign at x = 0. true that f ′(x) Example For the functions function is from concave up Example and 22, concave use the down. second Find derivative the inflexion to find the inter vals where the points. 2 x 3 a f (x) = 4 2 2x – 3 3x − 12x f b (x ) = c f (x) = x 2 x 1 Answers 3 a f (x ) 2 2x = − 3x − 12 x 2 f f ′( x ) ′′( x ) 12 x 6x = − 6x = 12 x − 6 = − 12 Find the Find where second derivative of f. − 6 f ″(x) = 0. 0 1 x = 2 signs of – f '' + Make a sign diagram for f ″ 1 x 2 1 ⎛ f is concave down ⎜ ⎛ is concave up on 1 f ″(x) < 0 and ⎠ ⎞ ,∞ ⎜ ⎝ since ⎟ 2 ⎝ f ⎞ −∞, on since ⎟ 2 f ″(x) > 0. ⎠ 1 Since f ″(x) changes sign at x , = there is an inflexion 2 3 1 ⎛ point ⎞ there. ⎜ ⎝ 2 1 ⎛ = f 2 ⎞ ⎛ 2 1 ⎞ ⎛ 3 ⎟ ⎜ ⎠ ⎝ 2 1 13 ⎞ = 12 ⎟ ⎜ ⎠ ⎝ 2 ⎟ ⎜ ⎠ ⎝ − 2 1 Evaluate ⎟ f at So the inflexion point 1 is find the 2 y-coordinate ⎛ to x 2 ⎠ of the inflexion point. 13 ⎞ , ⎜ ⎝ ⎟ 2 2 ⎠ 2 x f b (x ) 4 = 2 x 1 6x f ′( x ) = 2 2 (x 1) 2 (x f ″(x) 2 − 1) (x ′′( x ) −6 (3 x − 1)( 2 x )] + 1) Find the second derivative of f. = 2 f 2 2 ( 6 ) − ( 6 x )[2 ( x = = 0 f ′′( x ) 2 + 1) (x = 2 3 (x 1) 2 −6 (3 x 2 4 is undefined 1) when To − 1) = 0 − 1 = 0 find a where sign f diagram ″(x) = 0 for and f ″ you where f must ″(x) is 0 3 undefined. 2 (x make 3 1) x 2 −6(3 x + 1) = 0 x = ±1 1 2 x = − 3 No real signs of f solutions – '' Even + x x –1 is concave = down on (−∞, −1) and (1, ∞) since f ″(x) < f is concave there f ″(x) are changes no sign inflexion at points. This because up on (−1, 1) since f ″(x) > f (x) is undefined at x = ±1. 0, In and ±1 1 is f though – this case the concavity is changing on 0. either side of a vertical { asymptote. Continued on next Chapter page 3 c f (x ) = x ′( x ) = 3x ′′( x ) = 6x 6x = 0 x = 0 2 f f signs of f – '' Find the second Find where f Make 0 f is concave down on f is concave up (0, ∞) (−∞, 0) since f ″(x) < 0, a sign on since f ″(x) > 0. Since f f signs at x = 0, there is an inflexion So (0) the point there. Find the the point is (0, 0). 7S questions where 0. inflexion Exercise In = 1 to 6, function inflexion use is the second concave up derivative and to concave (x) = 2x − 3 f (x) = x 5 f (x) = 2xe 4x 3 − 3 2 f (x) = −x 4 f (x) = x 2 − 6x the inter vals down. 4 f find points. 2 1 3 + 4x 4 + 12x 1 x f 6 (x ) = 2 x Exam-Style + 1 Questions 24 7 Let f (x ) = 2 x + 12 48 x Use a that fact that f ′( x ) to = 2 show that the second 2 (x + 12 ) 2 144 ( x derivative is f ′′( x ) 4) = 2 (x b 8 i Find the relative ii Find the inflexion The graph of the 3 + 12 ) extrema second points of of derivative the the graph graph of of f f of y f is shown. Write down the inter vals 4 on which f is concave up and concave 3 down. Give inflexion the x-coordinates of any 0 –1 –2 –4 –5 and derivatives = f ''(x) 1 points. –1 Limits y 2 –3 diagram at 3 = 0. for f ″ x = 0 to find the ″(x) y-coordinate (0) = f. and Evaluate f ″(x) of + x changes derivative x of the inflexion point. The the first and graph of asymptotes Example Sketch second the to derivatives function. help We complete of can the a function also use tell us much intercepts about and graph. the intercepts graph and of each function. asymptotes to help Use the information draw the graph. you found in Examples 22–24 and 2 x 3 a f (x) = 2x 4 2 − 3 3x − 12x f b (x ) = f c (x) = x the x-intercepts, 2 x 1 Answers 3 a f (x) = 2x 2 − increasing: 3x − 12x (−∞, −1) decreasing: and (−1, 2) relative maximum: relative minimum: (−1, 7) (2, −20) 1 ⎛ concave ⎜ ⎟ 2 ⎝ ⎛ ⎞ −∞, down: concave (2, ∞) 1 ⎠ ⎞ , ∞ up: ⎜ ⎝ To ⎟ 2 find and ⎛ inflexion set the function equal to 0 equal to 0 ⎠ 1 13 ⎞ 2 x , point: ⎜ ⎝ solve: 3 2 − 3 x − 12 x = 0 ⎟ 2 2 ⎠ 2 x (2 x x-intercepts: y-intercept: (0, 0), (−1.8, 0), − 3 x − 12) = 0 (3.31, 0) (0, 0) 3 x 0 or x x 0 or x 9 4(2)( 12) y 2(2) relative maximum x 0 –3 1.81, 3.31 –1 To find the y-intercept evaluate To find the x-intercepts, f (0). –5 Inexion point –10 –15 –20 relative increasing concave decreasing down minimum increasing concave up 2 x b f (x ) 4 = 2 x 1 increasing: (−∞, −1) decreasing: relative (0, 1) and minimum: concave down: concave up: and (−1, 0) (1, ∞) (0, 4) (−∞, −1) and (1, ∞) and (−1, 1) set the function solve: 2 x 4 2 inflexion points: none 0 x 4 0 x 2 2 x x-intercepts: y-intercept: (2, 0), (0, 4) 1 (−2, 0) To find the y-intercept evaluate { f (0). Continued on next Chapter page ver tical asymptotes: x = To find the vertical asymptotes, find where the ±1 denominator equals 0 (check to see that the numerator is not 0 for that same value): 2 x horizontal asymptote: y = − 1 = 0 ⇒ x = ±1 We learned that the horizontal asymptote of 1 ax of y the form a function + b = is found by using the leading cx + d a coefficients, y . This = method works for any rational c function the where degree of the the degree of the numerator is equal denominator. 1 y = ⇒ y = 1 1 y Limit notation can be used to describe the 8 asymptotes. showing relative us The that horizontal for large asymptote positive y = values 1 is of x, y minimum gets 2 of 0 x, close y to gets 1, and close to for 1. small Using negative limit values notation to x –2 –3 –2 say this we write: lim f ( x ) = 1 and x →∞ lim f (x) = 1 x → −∞ –4 For the ver tical asymptote x = 1, as x gets –6 close to 1 from the left side of 1, y grows –8 large decreasing concave and positive without bound, down up down x gets y grows Using close to large limits 1 from and to the right negative say this we f (x) = side without write: 3 c and as increasing of 1, bound. lim f (x) = ∞ x →1 x and lim f (x) = ∞ + x →1 increasing: (−∞, ∞) Similarly, no relative lim f (x) + down: concave up: (−∞, 0) x → −1 (0, ∞) point: (0, 0) x-intercept: (0, 0) y-intercept: (0, 0) y 8 6 4 2 Inexion point 0 –5 –4 –3 –2 –1 x 1 2 3 4 –2 –4 –6 –8 increasing concave Limits and x = −1 down concave derivatives we write: lim x → −1 and concave inflexion for extrema up 5 = ∞ f (x) = −∞ to Exercise In 7T questions and second intercepts 1 to 4, sketch derivative and to the graph analyze key of the function. features f (x) = 3x the 3 + x + 2 x 4 the graph. first Find any asymptotes. 2 1 of Use 10x − 8 2 f (x) = x 4 f (x) = (3 6 f (x ) 2 + x − 5x − 5 4 f 3 (x ) = x x e f 5 (x ) − x) 2 e x = 1 = 2 2 Given it is the graph possible Example a Given to Given of f that graphs of any sketch a one of graph the of three the + 1 functions f, other two f ′ or f ″, functions. that graphs b x of the ′ the f graph and f graph and f shown is a graph of f, shown is a graph of f sketch the y ″ ′, sketch the ″ 0 x –2 –3 5 6 Answers a The y y y = = increasing at x = at x = changes and has a from decreasing 2. This 2 and means relative changes that f minimum from ′(x) equals negative to zero –2 x –1 5 6 The graph that f ′′(x) of is f ′′(x) is the f ′′(x) must f is always always concave positive. positive. derivative of f up. This means Since ′(x), a linear function, f '(x) = y b Since y = to f f ''(x) –3 y of f(x) 0 y graph = from f ''(x) f ′(x) be a positive equals positive to zero constant. when negative, the x = −1 graph and of f changes has a f '(x) relative Since from f maximum ′(x) equals negative to point zero when when positive, the x x = = −1. 5 and graph of changes f has a x –6 y = f(x) –2 relative Since f minimum ′(x) has x = 2, the x = 2. Since negative x > 2, f a graph for f x ′′(x) is < is point when relative of f ′′(x) concave 2. Since positive x = 5. minimum equals down f for is x when zero for x concave > when < 2, up f ′′(x) is for 2. Chapter Exercise 7U Exam-Style The 1 graph y Questions of y = f (x) is given. y Sketch a graph of y = f ′(x) and y = f = f(x) ′′(x). 0 –3 The 2 graph Sketch a of the graph derivative of y = f (x) of f, and y y = = f f ′(x), is x –2 given. y ′′(x). y = f '(x) x –3 The 3 is graph given. of the Sketch second a graph derivative of y = f (x) of f, and y y = = f f –1 ′′(x), y ′(x). 0 –2 –4 x –1 y . More on extrema and = f ''(x) optimization problems Y ou have seen how to use the second derivative to determine See concavity and inflexion points for a graph of a function. The Chapter second Section derivative This is of a called function the can second also be used derivative to find relative extrema. test If Second derivative f ″(c) then If f ′(c) near c, = 0 and the > 0 near c, test second derivative of f up exists So then f is near f concave c has a relative minimum. 1 If f ″(c) > 0, then f has a relative minimum 2 If f ″(c) < 0, then f has a relative maximum 3 If f ″(c) = 0, the at x = c If at x = f ″(c) then second derivative test fails first derivative test must be used to locate f is Limits f has a extrema. and derivatives c, concave near maximum. near c the So relative 0 and down the < c relative 2.6. 17, Example Find the relative extreme points of each function. Use the second derivative test whenever possible. 3 a f (x) = 2 x − 5 3x − 2 b f (x) = 3x 3 − 5x Answers 3 f a (x ) = 2 x − 3x − 2 2 f f ′( x ) ′′( x ) = 3x = − 6x 6x Find the first and Find the values second derivative of f. − 6 2 3x − 6x = 0 of x where the first derivative equals zero. 3x ( x − 2) x = 0 = 0, 2 f ′′( 0 ) = −6 f ′′( 2 ) = 6 f (0 ) = f (2) = > −2 relative < 0 0 ⇒ ⇒ ⇒ relative relative ( 0, −2 ) is maximum first minimum rel lative ⇒ is second f ′( x ) of the implies a relative maximum and f ″ > 0 implies a relative minimum. find a the the function relative where minimum the and extrema occur maximum to values. minimum 5 = zero derivative. 0 Plus (x ) each < help on CD: demonstrations f at ″ GDC b derivative f Evaluate ( 0, −6 ) the a maximum −6 Evaluate 3 3x and GDCs Casio are on Alternative for the TI-84 FX-9860GII the CD. − 5x 4 2 = 15 x 2 − 15 x = 15 x (x + 1)( x − 1) Find the first and Find the values second derivative of f. 3 f ′′( x ) = 60 x − 30 x 4 2 15 x − 15 x = 0 = 0 = 0, 2 15 x (x + 1)( x − 1) x f ′′( 0 ) = f ′′( −1) f ′′(1) signs of = f 0 = ⇒ second −30 30 > < 0 0 ⇒ ' x ⇒ x where the first derivative zero. ± 1 derivative relative e relative – –1 equals of test fails maximum Evaluate first the second derivative at each zero of the derivative. f ″ = 0 implies the f ″ < 0 implies a relative second maximum, derivative f ″ > 0 implies a relative minimum. test fails, minimum and 0 0 1 { Continued on next Chapter page Since is no at there is relative that no sign change minimum or in f ′ at x = 0, Since there use maximum f point. ′ the the first ( −1) f (1) = 2 ⇒ ( −1 , 2) is a relative maximum is a r elative minimum find = −2 ⇒ (1 , − 2) the GDC at the on and CD: GDCs Exercise Find Use the the Casio are on = test test to failed see if at the x = sign 0, of 0. function demonstrations Plus x relative help derivative derivative changes Evaluate f second where minimum the and extrema occur maximum to values. Alternative for the TI-84 FX-9860GII the CD. 7V relative second extreme derivative points test of each whenever function. possible. 2 1 f (x) = 3x 3 f (x) = x 5 f (x) = (x 2 − 18x 4 − 48 2 f (x) = (x 4 f (x) = xe 6 f (x ) 3 − 2 − 1) x 4x 1 4 − 1) = 2 x We have been finding relative or local + 1 extrema of functions. We can The also find the absolute or global extrema of a function. of the of extrema are the greatest and least values function over domain. Absolute extrema occur at either the a relative function minimum endpoints of a an the inter val at an derivatives the Relative never endpoint function. on near point. extrema and values function critical Limits and function. of are extrema maximum or extrema its the entire relative Absolute occur of a Example D a Identify each minimum, b Find the a labeled relative absolute point as an maximum maximum absolute or and maximum minimum, or or B neither. minimum 2 for f (x) = x − 2x on −1 ≤ x ≤ 2. A C Answers a A is neither. The points values and the those value absolute A on the greater below of graph than the the the endpoint be of a black function maximum cannot above value nor relative the line at an the of black the have A. So values A absolute extrema line function is have at less neither A than an minimum. since A is at an function. D B A C B is a relative B maximum. cannot values of function C is an absolute minimum and relative C is its is an absolute at of of entire The maximum. absolute function maximum greater than since the there value are of the B. C is minimum the least since value the of value the of the function over domain. value the an the absolute function minimum. D an be of the function function over its at D entire is the greatest value domain. 2 b f (x) f = x ′( x ) 2x − 2 x − 2x = 2x = 0 on −1 ≤ x ≤ 2 − 2 Find the critical numbers where f ′(x) = 0. = 1 2 f ( −1) = ( −1) − 2 ( −1) = Evaluate 3 2 f (1) = number (1) − 2 (1) = the in function the at each inter val. The endpoint largest and value is critical the −1 maximum and the smallest is the minimum. 2 f (2) The = (2) − 2( 2 ) absolute = 0 maximum of 2 f (x) = x absolute − 2x on −1 minimum ≤ is x ≤ 2 is 3 and the −1. Chapter Exercise Identify 7W each maximum labeled or point minimum, a in questions relative 1 and maximum 2 as or an absolute minimum, or neither. C 1 2 C A A B B D Find on the the absolute given maximum and minimum of the function inter val. 3 3 f (x) = (x − 4 f (x) = 8x 5 f (x ) = 2) for 0 ≤ x ≤ 4 2 − x for −1 ≤ x ≤ 7 3 3 2 x − x for −1 ≤ x ≤ 2 2 Many practical minimum an area or For 1 For minimize o p t i m i za t i o n ➔ problems values. optimization Assign 2 Write 3 Find an a ≤ x ≤ since occur Limits that or and in maximum want proble m s to are the to are the equals you or maximize c al le d derivatives be optimized of two quantities to be sketch. (minimized or variables. or derivative have a feasible of the minimum derivative ′ (x) a and for the equation problem to be zero. maximum f draw sensible remember when quantities possible terms that second b, given When where optimized Verify to equation values situation first Such may problems: variables maximized) c o st. finding we problems determined. 4 involve example, = that or 0 test. the If at maximum domain endpoints minimum or or the an on a is must closed endpoint. using such be the that tested inter val can Example The product number of plus two three positive times the numbers second is 48. Find number is a the two numbers so that the sum of the first minimum. Answer x = the first y = the second S = x positive number positive Assign = + 3 y Write 48 ⇒ y to the quantities to be deter mined. number an equation for the sum, the quantity to be minimized. 48 xy variables = x S = x ⎛ 48 ⎞ ⎜ ⎟ + 3 144 = x ⎝ x Use the other given infor mation to rewrite the + equation x ⎠ for the sum using only two variables. 144 S ′( x ) Find = 1 the derivative of the equation to be minimized 2 x and then find the critical numbers, where the 144 derivative 1 − = equals 0. 0 2 x 2 x = 144 x Since only = ±12 the x = numbers are positive consider 12. 288 S ′′( x ) = Use 3 the second derivative test to verify that the x critical number 12 gives a minimum. Note that the 288 S ′′ (12 ) = > 0 ⇒ relative minimum first derivative test could also be used. 3 12 48 y = 48 ⇒ y = = 4 Find The numbers Example A second number. four th enclose are 12 and 4. rectangular The the 12 x plot side the of of farmland the maximum plot is area. is enclosed bordered Find the by by a 180 m stone maximum of wall. fencing Find material the on three dimensions of sides. the plot that area. Answer Make to w be a sketch and assign variables to the quantities deter mined. w l Write A = an equation for the area, the quantity to be lw maximized. 2w + l = 180 ⇒ l = 180 – 2w 2 A = (180 – 2w)w = 180w – Use the other equation A′(w ) = 180 − 4 w 180 − 4 w = 0 Find and the then for = the infor mation area derivative find derivative w given to rewrite the 2w the equals using of the critical only two equation numbers, variables. to be maximized where the 0. 45 { Continued on next Chapter page Use A′′(w ) = the critical A′′( 45 ) = −4 < l = 180 – 2w l = 180 – 2(45) A = A 45 m second derivative test to verify that the −4 90(45) by 0 ⇒ relative = 45 gives a maximum. maximum Find ⇒ = number the length and the area. 90 4050 90 m plot will have the maximum 2 area of 4050 m Exercise 1 The so sum that The of the second 2 7X two sum of number sum number of is positive is one 200. the a numbers first is number 20. and Find the the two square numbers root of the maximum. positive Find the number two and twice numbers so a second that their positive product is a maximum. 3 A rectangular and the built pen from figure. 400 What is par titioned feet of into fencing dimensions as should two sections shown be in used y so that the area will be a maximum? x Example Find area the of dimensions 192 square of an open centimetres box that with has a a square base maximum and surface volume. Answer Make to a the sketch and quantities assign to be variables deter mined. h x Write an equation for the volume, the x quantity to be maximized. 2 V = x h Since 2 x is + 4 xh the the box sum is of open, the the area of surface the area bottom = 192 2 of the box, x , and the area of the 2 192 h x = four lateral faces, 4xh. 4 x 2 ⎛ 192 x ⎞ 2 V (x ) = x ⎜ ⎟ 4 x ⎝ Use this to rewrite the equation for ⎠ the area using only two variables. 1 3 = 48 x x − 4 { Limits and derivatives Continued on next page x Find the derivative of the equation 3 2 V ′( x ) = 48 − x to be maximized and then find the 4 critical numbers, where the derivative 3 2 48 − x = 0 equals 0. 4 3 2 x = 48 4 2 = x x 64 ±8 = The feasible is x = V ′ ′( x ) critical number 8. Use 3 = that 2 ′ ′(8) second derivative test to verify = the critical number 8 gives a maximum. 3 V the x − (8 ) = −12 < 0 2 ⇒ relative maximum 2 192 − h 2 x 192 = ⇒ h = 4 x The Find 4 the height of the box. 4 (8) dimensions maximum by − 8 = area of the are box 8 cm with by 8 cm 4 cm. Example 10 000 The cost C of ordering and storing x units of a product is C (x ) = x . + A deliver y tr uck can x deliver at most 200 units per order. Find the order size that C the will minimize the cost. Answer 10 000 C (x ) = x + where x is the number of units. is function to be minimized. of the x 10 000 C ′( x ) = 1 − 2 x Find the derivative equation to be minimized 10 000 and 1 − = then find the critical numbers, where the 0 2 x derivative equals 0. 10 000 = 1 2 x 2 x = 10 000 x The the no = ±100 feasible order more absolute critical must than number include 200 at units, minimum for 1 is least we ≤ x x = need ≤ 100. one unit to Since and find the Since the endpoints must be function and is zeros considered defined of for the the on a closed derivative minimum in inter val, the the inter val value. 200. { Continued on next Chapter page 10 000 C (1) = 1 + = 10 001 1 10 000 C (100 ) = 100 + = 200 ⇐ minimum cost 100 10 000 C ( 200 ) = 200 + = 250 200 The 100 minimum cost occurs when there are units. Exercise 7Y 3 1 An open Find 2 the box with that the 3 = how 3 A square dimensions Suppose C(x) a of base the average box cost and that of open top minimize producing x x – 3x many – 9x items + 30. should moves on a If at be most 10 produced the at 4 A time t is maximum Exam-Style ✗ the volume surface units horizontal items to cylinder given by line distance s(t) = t so of an of 32 000 cm . area. item is given by be that its produced the cost position in for a the day , day? from 2 – between can minimize 3 origin Find a 2 par ticle the has 12t the +36t par ticle –10 for and 0 the ≤ t ≤ 7. origin. Questions is inscribed in a cone with radius 6 centimetres 10 and a height 10 Find an of the h, – h centimetres. expression height of for the r, the radius of the cylinder in terms r 10 cm cylinder. h b Find c Find an expression of the volume, V , of the cylinder in terms of h 2 d dV V and 2 d 5 Hence Let x be 6 cm dh dh find the the radius number of and height thousands of of cylinder units of with an maximum item volume. produced. The revenue for 2 selling a x The units profit is r (x ) p(x) = 4 r(x) – x and c(x) the Write cost an of producing expression for x units is c (x) = 2x p(x). 2 d dp b Find p and 2 dx dx c Hence the find the number of units that should profit. Review exercise ✗ 1 Differentiate with respect to x a 4x 3 4 3 3 2 +3x – 2x + 6 x b c 4 x 2 d (x Limits 3 – 1)(2x and x 4 x + 7 2 – x derivatives 4x + x) e f e be produced in order to maximize ln x 3 g 4 (x + 1) ln(2x h +3) i 2 x x 2 4 x 2x 2 j 2e x (3x k + 1)(e ) l x e 6 3 1 ⎛ 2 m 3 2x 5 e ln o ⎜ ⎟ x ⎝ Exam-Style ⎞ 2x x n ⎠ Questions 3 2 Let f (x) = 2x – 6x 3 a Expand b Use (x + h) f the formula f ′( x ) = (x + h) − derivative c The graph d Write e Find of down the of f f is f (x) is 6x inter val show that h – decreasing ″ (x) (x ) to h →0 the f lim 6. for p < x < q. Find the values of p and q. . on which f is concave up. 2 x 3 Find at the the equation point of the normal line to the f cur ve (x ) = 1 4 xe (1, 4). 3 4 5 Find the coordinates at which A graph a the of Write tangent y = f down (x) f on the line is (2), f is graph of parallel f (x) to the = 2x 3x line y = + 5x 1 – 2 y given. ′ (2) and f ″ (2) in order 4 from y = f(x) 3 the greatest value to the least value. 2 b Justify your answer from par t a 1 3 6 A cur ve has the equation y = x (x – 4) 0 x 1 2 3 4 5 –1 2 dy a d y –2 Find i ii 2 dx b c For this A the x-intercepts iii the coordinates Use your the answers indicating par ticle from moves origin a Find the b Find when c Show Use a Find is the the of to the par t the coordinates points b to features a you by s (t) function par ticle is of for = relative minimum to limit examine or state each that a graph found line 20t – in such 100 of the cur ve, par t b that ln t, t its ≥ displacement 1. to the par ticle is left. always increasing. it function does not graphically and numerically . exist. 2 2 1 a 1 lim x →2 b x 2 point s moving the the inflexion. sketch horizontal given velocity of of exercise GDC the O the ii along velocity that Review 1 find: i clearly 7 cur ve dx x lim x →3 c x 2 x →4 x 16 d lim x →1 x 4 + 3 lim x 1 Chapter Exam-Style 2 A 10 foot Question post and per pendicular the on a top the of to each ground a 25 the foot post ground. pole and between are the two an expression for y ii Write an expression for z write an in in expression 30 a as apar t single of terms of L(x), and and shown terms for feet lengths y by poles, Write Hence of attached i iii stand Wires z r un stake in the at from a point figure. x x the total length of z 25 ft y wire used for both poles. 10 ft dL b Find i 30 x – x dx Hence ii 10 find foot CHAPTER the pole 7 in distance order to x the stake minimize should the be placed amount of from wire the used. SUMMARY n The tangent line and derivative f The function defined (x + h) − f is h →0 derivative is defined by f ′( x ) = Power rule If = n ● f (x) = y = Sum If f cf or (x) More derivative of f. (x + h) − f (x ) dy h f = or dx (x + h) − f (x ) lim h →0 h then f ′(x) = nx , where n ∈ rule where c multiple (x), u(x) rules ± is c real number, then f ′(x) = 0 is any real number, then y ′ = cf ′(x) rule v (x) for any rule where dierence = the n−1 , c, Constant If x Constant If f (x) as lim h →0 known h f The x (x ) lim by of then f ′(x) = u ′(x) ± v ′(x) derivatives x Derivative e of x If f (x) = e Derivative x , then of ln f ′(x) = e ′( x ) = x 1 If f (x) = ln x, then f x The If f product (x) The = rule u(x) · v (x) quotient then f ′(x) f u(x) · v ′(x) + v(x) · u′(x) rule v ( x ) ⋅ u ′( x ) − u ( x ) ⋅ v ′( x ) u( x ) If = then ( x ) = f ′( x ) = 2 v(x ) [v ( x )] Continued Limits and derivatives on next page The The If chain f chain (x) The = rule and higher order derivatives rule u(v(x)) chain r ule then can f ′(x) also = be u ′(v(x)) · v′(x) written as: dy If y = f (u), u = g (x) and y = f (g(x)), dy ⋅ dx Rates The of change instantaneous and rate of s (t function, (t ) = The change + h) − s of = rate of function , derivative change a (t ) = of the function is decreasing, When a function is increasing, = v ′( t ) the tangent tangent lines lines ′(x) > 0 for all x in (a, b) then f is increasing f ′(x) < 0 for all x in (a, b) then f is decreasing is used to first f If f f ′(x) at if f ′′(x) More For f = on for is 0 Write all negative in f the curve curve have have negative positive slope. slope. It locate on (a, b). on relative (a, b). extrema of f. If f is defined at a to negative at x = c, then f has a relative maximum to positive at x = c, then f has a relative minimum then ′′(x) on down f is (a, b). points . changes and concave A The up on points point on (a, b). on the a If f graph graph of ′′(x) < where f is an 0 for the all x in concavity inflexion point sign. optimization problems problems: to given draw a to quantities and quantities to be determined. sketch. be optimized (minimized or maximized) in terms variables. the 0 that of the you are or the at sensible equation have domain since = (a, b) inflexion equation that If ′ (x) from variables values tested positive concave and an Verify test. from x possible two Find test extrema Assign f to the (c)). called derivative to (c)). optimization of (c, f are When s ′′( t ) then: changes 0 then changes (c, f at > c changes ′(x) ′′(x) (a, b) derivative number point If = that: point the f If the h If is (t ) If The the veloci ty graphing a critical and velocity + h) − v lim When follows is s ′( t ) h →0 line displacement v (t The a dx h instantaneous acceleration in du (t ) lim h →0 motion du = then a is feasible be such that or for optimized minimum maximum an or to a or ≤ the maximum x ≤ b, minimum problem equals using remember on a situation where the zero. closed the that first the inter val or second derivative endpoints must can when occur be endpoint. Chapter Theory of knowledge Truth Inductive Inductive in reasoning . looks reasoning generalization. this mathematics Use at inductive par ticular reasoning cases to to make a make a conjecture about problem. Copy the the circles points on and each table. circle. Draw Count all possible the number chords of connecting non-overlapping The regions in the interior of each the results in the comple table. If you based of points on the Number of on the for the regions number circle your obvious pattern Number you. for ted conjecture most y alread are s circle Record two first circle of regions formed formed, 2 find 2 not 3 you that true will it was for n = 6. 4 4 5 . Describe, regions in words, any patterns you obser ve for the number of formed. How does a have to before it . Make that a conjecture are formed mathematical many by about the number connecting n of points non-overlapping on a circle. Write is Use your to it as a Can we know predict the number of regions repeat we it ever is true all possible chords connecting six points on a by formed inspecting when know regions expression. conjecture pattern true? always . times circle the are pattern? drawn. . Draw a circle with six points. Draw all the possible Does we connecting the points to check your prediction this mean chords from question should never 4. use inductive reasoning? Theory of knowledge: Truth in mathematics Deductive reasoning n In Section 7.1 we conjectured that the derivative of f (x) = x n−1 is f '(x) = nx . 5 We confirmed reasoning In to deductive base that the provide conjecture validity reasoning deductive we reasoning to was our reason on tr ue from basic for f (x) = . x We can use deductive conjecture. the axioms, general to the definitions specific. and In mathematics we theorems. n Use the definition of derivative n−1 f '(x) = nx f '(x) = lim and the binomial theorem to show that if f (x) = x then + for n ∊ n f (x + h) – f Apply (x) the denition of derivative to f(x) = x and n h→0 then h n (x = + use the binomial theorem to expand (x + h) n h) – x lim h h→0 n n ( ) [ = 0 n x 0 h + n n ) ( 1 n−1 x ) ( 1 h + 2 n−2 x n ( 2 h +...+ ) 1 x n –1 n−1 h + ) ( n 0 x n h ] – n x lim h h→0 n n [x = n ( n−1 + nx h + ) 2 n−2 x ( 2 h +...+ ) n−1 n xh n –1 + h ] – Simplify n where possible x lim h h→0 n n = Collect ( n−1 nx h + ) 2 n−2 x ( 2 h +...+ ) n−1 xh n –1 like terms n + h lim h h→0 n n [nx h = ( n−1 + ) 2 ( n−2 x h +...+ Factorize ) n –1 n−2 xh n−1 + ] h lim h h→0 ( n−1 [nx lim + Simplify n n = ) 2 ( n−2 x h +...+ ) n−2 xh n –1 n−1 + ] h h→0 n n ( n−1 = nx + Evaluate ) 2 ( n−2 (x )(0) +...+ ) n –1 n−2 (x )(0) the limit n−1 + (0) n−1 f '(x) = nx Can we now true for all say for cer tain that the conjecture will be + The A classic 'math physicist a astronomer , a mathematician physicist were ∊ ? disagreed: Why or “No! why not? What kind of reasoning was joke' Some An n Welsh sheep are black!” the mathematician using? and traveling re through Wales by train, when is they saw middle of a a black sheep in at least eld. astronomer said: sheep are at least one “All side Welsh eld, the sheep, The one of which is black!” black!” Descriptive CHAPTER 5.1 OBJECTIVES: Population, sample, presentation histograms outliers; width, 5.2 of data: with class data: boundaries and measures. Cumulative Before use Y ou 1 should Draw e.g. a Draw distributions of modal mid-inter val bar continuous (tables); and frequency whisker values for plots; calculations, tendency: range, mean, interquar tile cumulative median, range, frequency mode; variance, in the inter val quar tiles standard and deviation. graphs. how Skills to: 1 char t for the number check Draw a bar char t families of 30 for this frequency of f Favorite children data; class. char t. a box and start know bar discrete inter vals; Central frequency; you sample, frequency equal grouped Statistical random percentiles. Dispersion: 5.3 statistics students color in the frequency table below . Red 6 Blue 8 y f Children 12 1 Pink 8 10 10 12 3 5 4 3 5 2 ycneuqerF 2 e.g. c Find the mean, a the median x 2 mode mean of 2, and b 3, the 3, 5, 4 3 of Mean = Mode = c Median 3 = 5 Descriptive statistics 6 median. mode 6, 7, 2 and 9 35 = 7 b 5 children 2 + 3 + 3 + 5 + 6 + 7 + 9 a 4 2 Number the Black 4 1 Find 9 6 0 2 Purple 8 = 7 a Find the mean of 4, 7, 7, 8, 6 b Find the mode of 5, 6, 8, 8, 9 c Find the median i 6, 4, 8, 7, ii 5, 7, 9, 11, 11, iii 6, 8, 11, of 2, 4 5 13, 11, 15 14, 17 table. Statistics are visible all around us. Averages (such as the y mean, 10 mode and median) and char ts (such as bar graphs, line graphs 9 and pie char ts) it. Y ou to media. have ever yday used We probably ever ywhere use statistics made conversation or some – from ever y business day statistical thinking. to without such to realizing statements Statements spor ts ycneuqerF fashion are as in ‘I your 8 7 sleep 6 for about eight hours per night on average’ and ‘Y ou are earlier’ are more 5 likely to pass the exam if you star t preparing 1875 1900 1925 1950 1975 2000 2025 x Year actually statistical in nature. Statistics Statistics is concer ned a ● designing ● representing experiments and and analyzing other data collection information to drawing ● estimating the from present or this the future. know help This chapter explains these techniques and how them to real-life science situations. used to of data. organize It is and data. chapter how your you on to can your do do GDC, them by most but if hand understanding. The of the you too, it will emphasis to is apply the tools calculations data predicting of analyze In conclusions set aid understanding ● is with: on the understanding results Statistical you tables examinations your and obtain, – are you interpreting in context. not will allowed need to in use GDC. Chapter Investigation – what test 32 students a test 1, 1, 2, 2, 2, 3, 3, 4, 7, 7, 7, 8, 8, 8, 8, 9, 10 What should How could How should Should What Can . you you of of use display an you draw any much Data is either the called and to that give from How your do you involves is in a your this single class. scores data. you that or can Comparing and data variable, Y ou will you 6, seen as to for their were: 7, 7, of see this the scores? grades? gather example, charts, in and or data pen school? computer do you Chapter is weights 10. classified as data data that describes can be counted that give quantitative include: How many How long to How own? and height averages measured. Questions color? the find data. information qualitative to letter heights Quantitative data. give travel 7, picture draw quanti tative sometimes favorite of results 6, scores? get brand 6, better data is What Their 6, a the the include: What 5, Quantitative is our data? conver ting analysis categorical Questions data scores? 10. 5, this the information data categories of 5, data Qualitative with analysis quali tative Qualitative out 5, with conclusions with bivariate 5, the about students more do do average? do analysis the called ➔ organize you 4, we scores? scored 4, teacher Univariate all and the you should Univariate is took 0, should pens does do it you take own? you to school? many computers have you owned? [ Is the data from our test scores qualitative or Discrete. quantitative? How ➔ Quantitative and ➔ A Here we A can be split up into two categories: discrete are of discrete working CDs that quantitative accuracy variable has exact numerical with values of , , , ,…, for you have or continuous depends instr ument do pairs you of own? on the the number variable accuracy of can of the example, children be values. in measured the your and family . its measuring used. [ Continuous variables, such as length, weight and time, may have Continuous. What the fractions many shoes continuous quantitative number ➔ data or decimals. Descriptive statistics is the train? speed of What is and sample? a When we the dierence think of the term between population , a we population usually think Population of people in our town, region, state or countr y . Sample ➔ In statistics, defined ➔ A part the Ever y 2 The the sample the we are population a has have has an called of two for all data a sample. individuals members driven It is from a a decisions. subset the of of population. characteristics: equal essentially includes studying is selection must oppor tunity the same of selection. characteristics A each of a The number b The length c The time d The number the test continuous . population population. Classify Are ter m that individual Exercise 2 of samples 1 1 g roup population, Random as the the of of following fish the taken caught catch friends scores either by an discrete or continuous data. angler. fish. to of as at the a fish. that star t the of angler the took chapter with him. discrete or data? Presenting A data bar char t column A frequency table is an easy way to view is sometimes called a graph. your y data Y ou quickly can and also look show for 8 patter ns. discrete data in a bar chart ycneuqerF 6 4 2 0 x 20 21 22 23 Cars Example A student inter vals counted for 30 how 22, 22, 24, 22, 23, 22, 27, 26, 25, 28, a this bar many minutes. 22, Draw 25 26 27 28 minute 23, Display 24 per data char t in a for His cars passed results 21, 23, 23, 27, 26, 22, 20, 21, 20. this house in one-minute were: 21, frequency his 21, 21, 22, 23, 25, 27, 26, 23, table. data. { Continued on next page Chapter Answer Tally Number of cars Tally each cor rect per data item in the Frequency row. Write the totals in minute the 20 || frequenc y column. 2 21 5 The 22 number times 23 21 appears 5 7 || in the data. 6 | 24 | 1 25 || 2 26 ||| 3 27 ||| 3 28 | 1 A y bar char t discrete is data suitable and may for have 8 gaps between the bars. ycneuqerF 6 Use the ver tical frequenc y and scale the for the horizontal 4 scale 2 0 21 22 23 Cars When in number of cars per x 20 ➔ for minute a you 24 per 25 27 28 minute have grouped 26 a lot of data, frequency you can organize it into groups table Why For continuous data, you can draw a histogram. It is in to a bar Example char t but it doesn’t have gaps between the are ages no gaps continuous data? bars. Only The there similar of 200 members of a tennis club frequency are: histograms 20, 22, 23, 24, 25, 25, 25, 26, 26, 26, 26, 28, 28, 29, 29, 29, 30, 30, 30, 30, 30, 30, 30, 32, 32, 33, 33, 33, 34, 34, 34, 34, 34, 34, 34, 34, 35, 35, class with inter vals equal will be examined. 35, 35, 36, 36, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 42, 42, 42, 42, 42, 42, 43, 43, 43, 43, 43, 43, 44, 44, 44, 44, 44, 44, 45, 45, 45, 45, 45, 45, 45, 45, 46, 46, 46, 46, 46, 46, 46, 46, 47, 47, 47, 47, 47, 47, 47, 47, 47, 48, 48, 48, 48, 48, 48, 48, 48, 48, 49, 49, 49, 49, 49, 49, 49, 49, 50, 50, 50, 50, 50, 50, 51, 51, 51, 51, 51, 51, 51, 52, 52, 52, 52, 52, 53, 53, 53, 53, 53, 53, 53, 53, 53, 54, 54, 54, 54, 55, 55, 55, 55, 55, 56, 56, 56, 57, 57, 57, 57, 57, 57, 57, 57, 57, 57, Having each us 58, 58, 58, 59, 59, 59, 60, 60, 60, 60, 63, 63, 64, 64, 64, 64, 65, 65, 68, 69. 60, 61, 61, 61, 62, 62, 62, 63, a age 63, a grouped frequency Descriptive statistics table and histogram for the data. { Continued on next page line would table deep! Draw one 50 for give lines Answer Age 20 ≤ age < 25 25 ≤ age < 30 30 ≤ age < 35 35 ≤ age < 40 Tally Frequency |||| 4 Equal 12 || 25 is class in the inter vals class 25 of ≤ 5 age years < 30 20 18 ||| 40 ≤ age < 45 26 | 45 ≤ age < 50 42 || 50 ≤ age < 55 31 | 55 ≤ age < 60 24 Numbers of |||| the like 60 ≤ age < 65 on bars the or edges an x-axis scale. 19 |||| No gaps between the bars Y ou 65 ≤ age < 70 |||| can use draw GDC histograms. Chapter to 17, See Section ycneuqerF 45 5.4. 30 15 GDC help on CD: demonstrations 20 25 30 35 40 45 50 55 60 65 70 Plus Exercise day the they T ime Casio the TI-84 are on FX-9860GII the CD. B EXAM-STYLE of and GDCs Age All Alternative for x 0 1 a 4 QUESTION IB students studied in a school mathematics. were The asked results how are many given in minutes the a table. spent studying 0 ≤ t < 15 15 ≤ t < 30 30 ≤ t < 45 45 ≤ t < 60 60 ≤ t < 75 75 ≤ t < 90 mathematics (min) Number of 21 32 35 41 27 11 students a Is b Use this data your represent continuous GDC this to help or discrete? you draw a fully labeled histogram to data. Chapter EXAM-STYLE QUESTION Number The 2 following table shows the age distribution of of Age mathematics teachers teachers the work a Is b How many High School? Use c to The 3 who data your at Caring discrete or represent following to this School. 20 ≤ x < 30 5 30 ≤ x < 40 4 40 ≤ x < 50 3 50 ≤ x < 60 2 60 ≤ x < 70 3 continuous? mathematics GDC High help teachers you draw work a at fully Caring labeled histogram data. histogram shows data about frozen y chickens 60 in ≤ supermarket. w < 2, the b Draw c How w mass the < of 3 and frozen grouped many so in are grouped such that on. chickens frequency frozen kg chickens discrete table are for there or continuous this in data? histogram. the rebmuN Is ≤ masses fo a 2 The snekcihc 1 a supermarket? 50 40 30 20 10 0 x 1 2 3 Mass The 4 histogram on the right shows how many minutes 4 5 6 (kg) y it 5 takes for a Is b Represent c What get data is to retur n discrete the the data or in shor test home after school. ycneuqerF the students continuous? a grouped time that a frequency student table. could take 4 3 2 1 to home? 0 x 5 10 15 20 T ime . A a Measures measure set of data tendency The ➔ of central lies. are of the The central tendency three mode, the tells most 30 35 40 45 (min) tendency us where common mean 25 and the the middle measures of of central Another median. word is ‘average’. mode The mode is the value that occurs most frequently in a set of data. The mode often. that in a list Remember mo st of numbers that does. mo de is the star ts number with the that same occurs first most two letters There than number Descriptive statistics more occurs once then there that be mode. than for can one in is set no more the no of If set, mode numbers. Example Find the mode of: 9, 3, 9, 41, 17, 17, 44, 15, 15, 15, 27, 40, 13 Answer The mode When the is (15 presented biggest the occurs with a the most frequency at 3 times). table, the mode is the group with frequency . Example Find 15 mode or modal class for a these frequency tables. b Goals Frequency 0 4 1 7 5 2 3 10 ≤ t < 15 6 3 3 15 ≤ t < 20 7 4 1 20 ≤ t < 25 6 T imes 0 ≤ ≤ Frequency t t < < 5 1 10 5 Answers a The mode is 1 goal. Common 1 2 The No. The The mode No. The is b The 15 modal ≤ t < Exercise 1 Find a class The is is 7. biggest is frequenc y is 7. 3. most common frequenc y 3. mode table 20. errors: mode is from called a the grouped modal frequenc y class. C the modes 7,13,18,24, of these sets of data. A 9,3,18 set of bimodal b 8,11,9,14,9,15,18,6,9,10 c 24,15,18,20,18, d −3, two 4, 0, −2, 12, 2, 7, 4, 2, 1, 9, 0, 0, 3.5, Find the mode of each a 3, 0, it is has modes. , 4 5 1 3 , 2 2 if 22,24,26,18,26,24 1 e data , 11 2 frequency table. b Goals Frequency Height Frequency 0 4 140 ≤ h < 150 6 1 7 150 ≤ h < 160 6 2 3 160 ≤ h < 170 5 3 3 170 ≤ h < 180 10 4 1 180 ≤ h < 190 8 Chapter The The the mean arithmetic most ➔ The of is mean common mean is numbers usually measure the in a sum set Sum of Mean of of of the mean data It representative score for teacher the us is a the single usually value. year always the mean or average and is tendency . numbers divided by the number data values = gives set. the data. Number of The called central number not For may gives data values a member example, be 85.73% scores that that of your even are indicates the data average though whole a center set but lower case Gr eek l etter μ is the pronounced Σ (which the tells sum pronounced a and mathematics N is us ‘mu’, to here) Is ‘sigma’ ‘nu’. your numbers. symbol for is often a misunderstanding t he between population is nd of There The μ the population mean and mean. sample mean. The population mean x Population μ mean = uses Greek letters whereas the N sample where Σx is the sum of the data values and N is of data Example Find the values in the uses and x n. uses only the population mean of 89,73,84,91,87,77,94 b 2, GDC help on CD: demonstrations 3, mean. population. a 3, Our the course number mean 4, 6, Alternative for the TI-84 7 Plus and GDCs Casio are on FX-9860GII the CD. Answers x a 89 73 84 91 87 77 94 Y ou N can calculate the 7 mean from a list on 595 your 85 GDC. In one- 7 variable x b 2 3 3 4 6 7 N 6 the 25 statistics GDC, the can also calculate is 6 Descriptive statistics the mean mean 4.16 x . The GDC calculates Y ou on from a frequency table. Σ x also and n. Example Find the mean of each set of data a displayed below . b (g) Grade 0 11 1 10 2 19 3 10 (a) Age Frequency Frequency 10 ≤ t < 12 4 12 ≤ t < 14 8 14 ≤ t < 16 5 16 ≤ t < 18 3 Answers a (g) Frequency fg 0 11 0 1 10 10 2 19 38 Grade Add f × The a 3rd column; fg means g. total of the fg column is the sum This of all of the it 3 10 is the as appears in the IB 30 The total of the f column is the Formula T otal formula grades. 50 78 number of booklet: grades. n ∑ fg ∑ Mean f x i i 78 i = = = μ 1.56 = 1 = n ∑ 50 f ∑ i b When (a) Age f data are grouped, we i can fm Mid calculate point (m) all 10 ≤ t <12 4 11 44 12 ≤ t < 8 13 104 14 the f = 1 of the the spread mean data by values around the assuming are that equally midpoint. This method small and that is ≤ t < 16 5 15 75 16 ≤ t < 18 3 17 51 often T otal 20 say, Mean = mean’. not mean = = ‘guess’ work out, – it as in 13.7 this example or with GDC. Lana’s mathematics she on get does 20 your Example It 274 274 f ∑ questions ‘estimate the means fm to why examination 14 leads inaccuracies the fifth test test grades in order are to 87, get a 93,89and mean of 85. 90 What for the score must term? Answer μ x = Select the mean for mula. N 87 90 + 93 + 89 + 85 + x Substitute the infor mation into the = for mula. 450 = 354 x = 96 Lana must + x score Solve 96 on her fifth for Answer x. the question. test. Chapter Exercise 1 Find D the mean driving speed for 6 different −1 road if their speeds are −1 66 km h cars on the −1 , 57 km h same −1 , 71 km h −1 , 69 km h , −1 58 km h and 54 km h Ronald . F isher (1890–1962) 2 The price $1.61, of buying $1.96 and music $2.08 from per different track. What sites was was the seen mean as $1.79, price? in the UK Australia called 3 A computer repair ser vice received the following number of and the day over a period of 30 5 6 9 7 4 2 4 7 8 3 4 9 8 2 3 5 9 7 8 9 7 5 6 7 7 4 6 2 4 practical the b Constr uct calls data per discrete a or biology The table table and find the mean number could of as day . sunshine below in the ≤ m first < the 100 (m) Minutes 0 shows be the 30 m < 60 16 60 ≤ m < 90 20 120 36 120 m ≤ < m a Is the b What < 150 data days of of the minutes year in of statistics.? of Newtown. or continuous? modal Find the mean number of minutes of Kelly’s get on five 6 the mean new Find fifth The player the must 8 in 82, order 76 to and 88. achieve What an score average of must 84 she on be of their the players team new family and in a the spor ts mean team goes is up 80.3 kg. to 81.2 kg. player. must vacation 300 km, they eleven the travel on 210 km, on mean total of the Tigger’s number Descriptive statistics of mean drive an time. On 275 km sixth day average the and in last shots 8 rounds of first to 250 km five 240 km. order that he of took formula days, How finish per day they many their golf in is the 71 8 shots. rounds? to travel km vacation What is technology seen papers. all time? The the 95, QUESTIONS Onceonly 220 km, of joins mass complete on are test mass EXAM-STYLE 7 scores tests? 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Answer 2, 5, 23, The of median numbers value is of this Write the numbers in order. There are 15 numbers. Our middle set number will be the 8th number: 23. GDC help on CD: demonstrations Plus and GDCs Y ou Casio are on can median nd Common ➔ If there are a lot of numbers and it is difficult to find the TI-84 FX-9860GII the on Alternative for CD. the your GDC. error. This the formula does not give ⎛ n +1 ⎞ middle member we can use the formula Median = th ⎜ ⎝ member, where n is the number of members in the ⎟ 2 the median. It the position of set. median Exercise Find a 2, the 3, median 4, 5, 6, of 7, 2, the 3, c 9, 3, 4, 6, 7, 2, 3, d 8, 1, 2, 4, 5, 9, 12, e 12, in the the data set. E The 1 gives ⎠ 4, 9, 1, 20, 7, following. 4 b 2, 19th-centur y Gustav 5, 5, 2, 7, 3, 8 median data, 0 0, 2, 4, 1.5, 8.4 Fechner into the although formal French and astronomer had used it German psychologist popularized the analysis of mathematician Pierre-Simon Laplace previously. 5 Chapter 2 Su has been collection. 3 counting Find the the number median of number tracks of on tracks the on CDs Su’s Number of tracks 7 8 9 10 11 12 13 Number of CDs 3 2 2 1 3 5 3 Find of the the mode, mean and median of our test scores in her CDs. at the star t chapter. Summary of measures of central tendency Advantages ➔ ● Mode The mode used data to for or be affect values the do ● not mode. when asked the Does of ● qualitative choose popular can Extreme Disadvantages the Not use data all be members set. necessarily may most not more unique– than one answer . ● item. 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Investigation What will amount Copy to happen to and all to data the the measures measures values, complete calculate – this mean, or Y ou and central central multiply table. mode of of each should median tendency data use value your each 6, 7, 8, 4 data to in data Now in by each the Multiply set piece each piece original same amount? Mode Median 14, 15, 16, 20 of of data 2. and complete happens to 4 the a If you add b If you multiply . the same GDC Mean 12, add the set. the copy what we set 14, Add 10, if by time. Data Data tendency to Measures of mean, each each Measures central the mode data data of following sentences and median to of explain the original data set. value……………………………………… value by 2…………………………………. dispersion tendency (mean, median, mode) explore the When middle of a data set. Measures of dispersion describe the spread data the data around a central you value. give set at you least measure ➔ The is range the difference between the largest and describe a of of should one central smallest tendency and one of values. dispersion. The be range is affected data For is the by measure values. It of dispersion doesn’t tell you to calculate how the but it can remaining distributed. example, lowest score is 0 10 simplest extreme – = for is 0 the test and the scores at highest the star t score is of 10. the chapter, Therefore the the range 10. Quartiles The less of median than data (25%) the into of of a of median, four the set data half equal separates greater. par ts. the data Quarti les Each of these into two separate par ts halves the – half original contains set one-quar ter data. Chapter ➔ F irst quar tile The of first the One also has into quar ter quar tile of and called the is quarti le way the the data. the data value lies three-four ths the 25th symbol one-quar ter below lies the above. percentile and rst It is often Q 1 Second quar tile The the second median also Third quar tile called The third way in. the It has the the 50th quarti le quar tile also the called set of name data for and is percentile. is three-quar ters of and the symbol another entire Three-four ths third is is quarti le of the data one-four th 75th of lies lies percentile the below above. and Q 3 1 Q 3 = (n + 1)th value and Q 1 = (n 4 the Y ou get statistical a minimum, maximum, median the first the third The (or where n is of data sense of values a data in the set’s data set. distribution by examining a five second quar tile), quar tile, quar tile. shows near value summary , or 1)th 4 number can This + 3 the GDC the extent to which the data is located near the median extremes. calculates these five values in One-Variable GDC help on CD: demonstrations Alternative for the TI-84 Statistics. Plus and GDCs Here is a five Minimum statistical F irst quar tile 65 Y ou you do tells 70 not 80. you and know half of First that test scores quar tile the a set Third 80 ever y the for Median 70 that above summar y = middle 70 but below and 50% of test quar tile third the and = 80 CD. are = tells are 90 between 90. Y ou can median on the Maximum half quar tile scores on 100 median 80 are FX-9860GII scores. 90 score, are of Casio Descriptive statistics a nd and GDC. the quar tiles See Chapter 17, 5.7 5.8. and Sections ➔ The the difference between interquarti le the third (IQR) range = and Q first − Q 3 The IQR is sometimes interquar tile range is called ‘the quar tiles is called . 1 middle half ’. Here the 20. Y ou can GDC to use the calculate interquar tile See Chapter Section ➔ A five statistical summar y can be represented graphically as a box and whisker 17, 5.9. Sometimes whisker the range. a plot box is and just plot. called a box plot. Range Whisker Interquartile Range Whisker The diagram drawn Min X Q m Q 1 Max X to example 3 should scale, on be for graph (Median) paper . The is first and shown by minimum plot third a are shows quar tiles ver tical at the the data line ends from are in of at the the page the box, ends and whiskers. of the the box, the maximum This box and median and whisker 268. Y ou can whisker draw box plots on and a x 60 70 80 90 100 110 GDC. See Sections GDC help on screenshots Plus and GDCs Extreme ➔ An or distant outlier is data any values value at are Chapter 5.5 CD: for Casio are on and 17, 5.6. Alternative the TI-84 FX-9860GII the CD. called outliers. least 1.5 IQR above Q 3 or below Q 1 Chapter Example a Find and the the range, the median, interquar tile range the of lower this set quar tile, of the upper quar tile scores. Y ou 18, 27, 34, 52, 54, 59, 61, 68, 78, 82, 85, 87, 91, 93, may explore b Show the data in a box and whisker wish to some of 100 misuses Check c if 18 is = 100 an outlier. Answers a Range – 18 = 82 Range = largest value smallest 18, 27, 34, 52, 54, 87, 91, 93, 100 59, 61, 68, 78, 82, 85, Write the data There are 15 in data in – value order. Median n 1 = 2 = 15 th 8th 1 th value = numbers value 2 the ∴ 68 n = set. 15. 1 Q = (n + 1)th value 1 4 1 = (15 + 1)th = 4th value = 52 4 3 Q = (n + 1)th value 3 4 3 = (15 + 1)th = 12th value = 87 4 IQR = Q – Q 3 = 87 – 52 = 35 1 Lower Upper quartile quartile b Median 0 c 10 20 Q – 30 40 50 1.5(IQR) 60 70 = 52 – = –0.5 80 90 1.5(35) = 100 52 – 110 52.5 Outliers are more than 1 ∴ 18 is not an 1.5 outlier. × below IQR Q or above Q 1 Exercise 1 The on 30, 75, Find a in 31 of the 55, 60, range, and a snow Januar y . 125, quar tile data QUESTION depths years 3. F EXAM-STYLE e box b the and Descriptive statistics at a All 75, the ski resor t data 65, is 65, 45, median, interquar tile whisker in plot. c the plot. are collected ever y year for 12 centimetres. 120, the range 70, 110. lower of the quar tile, data set d the and upper show the of statistics. EXAM-STYLE Here 2 76 are QUESTIONS Albie’s 79 76 test scores 74 75 for the 71 year. 85 82 82 79 81 Y ou Find a the range, the b median, c the lower can draw the d upper quar tile and e the interquar tile range of the data scores Here 3 are ever y and the hour 10, 11, Find a 12, the quar tile Use 4 c the the of 6 Match e data data in in in °C 21, the 25, median, box and below quar tile, box at 27, interquar tile a a a and hill d to the c 28, whisker resor t in Montana the whisker find a upper the lower of quar tile, the data d the 8 4 plots. taken upper plot. range, quar tile b and the e median, the interquar tile data. each 3 whisker set. 9 box 10 11 plot with the correct histogram. c x 2 and plot. b 1 to and 29. range a 0 GDC hours. 22, b the plot the 7 eleven 18, range, lower range 5 for box the temperatures 14, and Show the show a histograms set box of use quar tile, 5 6 7 8 9 x 10 0 1 2 3 4 5 6 7 8 9 x 10 0 1 2 3 4 5 6 7 8 9 10 y y i ii iii 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 7 6 5 4 3 2 1 0 x 1–2 3–4 5–6 7–8 9–10 0 x 1–2 . ➔ Cumulative To calculate the 3–4 5–6 7–8 0 9–10 x 1–2 the data cumulative values 5–6 as you go frequency add up the frequencies is cumulative cumulative frequency diagram or ogive is most useful when often diagram called calculate the median, quar tiles and percentiles of a large set a tr ying cumulative to 9–10 along. frequency A 7–8 frequency A of 3–4 frequency of graph. grouped or continuous data. Chapter Example 50 batteries were tested to see how long they lasted. The T ime results (in hours) are shown in the table. Draw a 0 frequency diagram and find the median and (h ) f < 5 3 10 5 cumulative ≤ h interquar tile 5 ≤ h < range. 10 ≤ h < 15 8 15 ≤ h < 20 10 20 ≤ h < 25 12 25 ≤ h < 30 7 30 ≤ h < 35 5 Answer Add (h) T ime f frequency 0 ≤ h < a ‘cumulative 5 3 3 10 5 8 8 16 cumulative frequenc y f 5 ≤ h < ≤ h < 15 by column adding Cumulative 3 10 frequenc y’ to the table. Work out the Cumulative up as you go. frequency 3 3 batteries than 15 ≤ h < 20 10 26 20 ≤ h < 25 12 38 5 3 + 5 = 8 8 ≤ h < 30 7 45 30 ≤ h < 35 5 50 y 8 3 + 5 + 8 = 16 10 3 + 5 + 8 + 10 12 3 + 5 + 8 + = 10 lasted less hours batteries than 25 5 10 lasted less hours 26 + 12 = 38 38 batteries lasted less 50 than ycneuqerf 40 25 hours Q 3 7 3 + 5 + 8 + 10 + 12 + 7 = 45 37.5 5 3 + 5 + 8 + 10 + 12 + 7 + 5 = 50 30 evitalumuC M 20 Q 1 12.5 10 Plot the upper limit frequencies. The 0 of first the two time points inter vals are (5, against 3) and the (10, cumulative 8) x 10 20 30 40 n T ime = 50 (h) 50 Median = = 25th data value 2 Draw a line For across from 25 large data sets, on n the the ver tical axis to the graph median is the then th 2 value. Median = 19 hours down to Read of f the time Q and axis. Q 3 from the 1 Values graph in the same and Q = 25, Q 3 IQR = (25 – 13) hours = 12 hours IQR = of quar tiles from a 13 = Q − GDC may be from values from a different Q 1 read cumulative frequency Descriptive statistics median 1 3 the way. graph. Exercise 1 The of G cumulative 100 frequency plot shows the reach in cm boxers. a Estimate the b What is c What does the median reach interquar tile the of a boxer. range? interquar tile range tell you? y 100 ycneuqerf 75 evitalumuC 50 25 0 x 60 65 70 75 Reach 2 The table computer Show this Length below 80 85 (cm) shows the length of 40 flash drives in a store. data f on a cumulative Upper frequency class Length diagram. Cumulative Sometimes (mm) (l boundar y mm) frequency continuous 6–10 0 10.5 l ≤ 10.5 0 11–15 2 15.5 l ≤ 15.5 2 16–20 4 20.5 l ≤ 20.5 6 given this. at in groups Plot the the upper boundar y, 21–25 8 25.5 l ≤ 25.5 14 26–30 14 30.5 l ≤ 30.5 28 data midpoint is like points class usually the between classes. 31–35 6 35.5 l ≤ 35.5 34 36–40 4 40.5 l ≤ 40.5 38 41–45 2 45.5 l ≤ 45.5 40 Chapter 3 The a table below distribution T ime (min) Number and under 6 6 and under 18 8 and under 24 10 and under 40 12 and under 60 14 and under 78 16 and under 92 18 and under 100 a scale for 2 your the The of minutes data in Find the 2 of in < 30 the IB on the axis, interquar tile to eat lunch. ver tical plot axis and draw the table and a represented of p and 8 ≤ t 8 < in range. the form of q 12 12 ≤ 36 t < 16 16 ≤ p students has table. Frequency m < 30 2 30 ≤ m < 40 3 40 ≤ m < 50 5 50 ≤ m < 60 7 60 ≤ m < 70 6 70 ≤ m < 80 4 80 ≤ m < 90 2 100 1 a Constr uct b Draw c Use a students horizontal mathematics ≤ < students t < 20 q QUESTION 20 m frequency diagram. the be t the 100 estimate values ≤ 10 24 Marks ≤ on ii Frequency shown to can a T ime EXAM-STYLE for frequency graph median below . class 1 cm by students 4 i of 0 Use 90 cumulative taken under cumulative A the times and 1 cm 4 shows the 2 Using b for a cumulative cumulative your graph to the median ii the upper iii the interquar tile Descriptive statistics frequency lower quar tiles range. table. diagram. estimate i and frequency the semester averages EXAM-STYLE 5 For ty The QUESTIONS students results Distance throw are shown (m) 0 ≤ 6 Constr uct b Draw a c If top < a 20 cumulative cumulative 20 ≤ your 20% of graph the to interquar tile e Find the median spor ts day . < 40 40 ≤ d < 60 60 15 ≤ d < 10 80 80 ≤ d < 100 2 table. the are considered qualifying for the final, distance. range. distance the school diagram. students estimate the shows d frequency frequency Find graph the 9 d The at 4 a use javelin below . d Frequency the the time thrown. that students listen to music during school. y 200 ycneuqerf 150 evitalumuC 100 50 0 5 10 15 20 T ime a 30 35 40 x 45 Estimate i the median ii the interquar tile iii the time top b 25 (minutes) The a time that students listen to music range student must listen to music to be in the 10%. minimum listening time represent this listening is 45 time minutes. is zero Draw a and box the maximum and whisker plot to information. Chapter EXAM-STYLE The 7 of QUESTION cumulative 220 frequency diagram below shows the heights sunflowers. y 220 200 180 ycneuqerf 160 140 120 evitalumuC 100 80 60 40 20 x 0 150 140 160 170 Height a Find b The go to The c the median smallest those tallest 190 (cm) height 25% are garden 10% 180 of sent shops? go to a sunflower. to home garden Between hotel what displays. shops. heights How many How are go many they? to the Y ou hotels? What is the smallest sunflower that goes to a may wish to hotel explore different visual display? representations The d middle half of the sunflowers are sold immediately . of How statistics. many The e of is this? height the of the shor test is tallest sunflower 136 cm. Draw a is 195 cm box and and the whisker height plot to Extension material Worksheet 8 central represent . The of range and but The a the 1 least three Squaring mean 2 the do Squaring many 3 The the of sunflowers. standard is calculated combines spread. between range It all is each the the are from good only values in arithmetic value between deviation and each the value measures two a data data set mean mean and of values. to produce the squared value. the mean value advantages: makes not each cancel adds more this from the in term values may be relatively subsequent Descriptive statistics below to weighting mean is positive weighting extra mathematics measure one difference cases fur ther of interquar tile variance measure Squaring and each differences at heights Variance spread ➔ the so that the mean. the larger is above differences. appropriate more since the In points significant. manageable statistical values when calculations. using this has - on CD: Measures tendency and of spread Because the differences are squared, the units of variance are Y ou not the same as the units of the should GDC to The standard deviation is the square root of the variance the same units as the the standard and deviation has a calculate population ➔ use data. and data. variance. ➔ The formulae for the variance and standard deviation are: n 2 2 σ = Population variance x = i 1 n n 2 σ = Population standard deviation x = i 1 n Example Thir ty Their 4, farmers were responses 5, 6, Calculate 5, 3, the asked how many farm workers they hire during a typical har vest season. were: 2, 8, mean 0, 4, and 6, 7, 8, 4, standard 5, 7, 9, 8, deviation 6, for 7, 5, this 5, 4, 2, 1, 9, 3, 3, 4, 6, 4 data. Answer Solution – ‘by hand’ The 2 Workers Frequency (x) (f ) (fx) (x μ) (x − μ) 2 IB syllabus covers deviation/variance ‘Calculation using only of standard technology’. This is f (x − μ) how 0 1 0 −5 25 25 1 1 1 −4 16 16 1 2 2 4 −3 9 18 3 3 9 −2 4 12 4 6 24 −1 1 6 5 5 25 0 0 0 you discrete would Calculate 2 Subtract 3 Square 4 Add 5 calculate variable the the each these Divide ‘by standard deviation for a mean. mean of from the squared this the hand’. total each results results by the obser vation. from step 2. together. number of obser vations. 2 This 6 4 24 1 1 4 7 3 21 2 4 12 6 Take gives the 3 24 3 9 27 9 2 18 4 16 32 30 To calculate the 150 root to get the standard σ mean: 5 fx n 30 To square σ 152 150 variance, positive deviation, 8 the calculate the standard deviation: 2 152 30 2.25 f (x ) n { Continued on next Chapter page Solution using Enter data Add the a new Press Press lists called page | workers to 1:Stat your and freq. document. Calculations . Leave the a dialogue number opens of another box. lists as dialogue 1 and box. press . Choose number from the drop down box for X1 List from the drop down box for the Frequency Press The screen. Y ou can standard ‘σ x: and freq list. . information The | Statistics… opens This in calculator 6:Statistics 1:One-Var This GDC σ x’ (the shown scroll will up deviation not and is population fit onto down the to value standard a see single it shown all. as deviation). n σ = 2.25 Y ou the (3 sf) should value always σx in use this GDC course, never use Plus value help and standard mean CD: Casio Alternative for the TI-84 FX-9860GII sx. GDCs The on demonstrations the and deviation gives an idea shows of the how much shape of variation the are on there the is CD. from the y distribution. Low ● Low ver y standard close to deviation the shows that the data points tend to sd be mean. High ● High standard deviation indicates that the data is spread out sd over x a large range Properties ● Standard of of values. standard deviation is only deviation used to measure spread or dispersion The around the mean of a data standard is ● Standard deviation is never ● Standard deviation is sensitive used widely to outliers. A single outlier data standard deviation and in tur n, distor t ● For data spread, ● If all zero with the of spread. approximately greater values of because a each Descriptive statistics the data the standard set value are is same mean, the greater the deviation. the equal same, to the the standard mean. science, the spor ts representation in can business, the to negative. describe increase deviation set. deviation is and medicine. Exercise Use 1 your Find sets 2 Find sets 3 GDC the of 7, a H mean, 12, the standard 32, 49 c 35, 65, 84, 27, 20, b and standard 30, 40, deviation table the illustrates the shoe deviation sizes of 4 5 6 7 8 f 9 14 22 11 17 50, for 28, 30, of their 73 the following 60 the following shoe of children below . Find in the the families mean and in 3 4 5 6 7 f 5 12 8 3 0 0 1 below shows studying Spanish standard deviation. f 9 could the number remember a class standard 2 5–9 a ballet class. sizes. 1 Words in QUESTIONS number table 44 students Children The for 66 standard shown 19, b Size The deviation numbers. 44, is and 37 variance EXAM-STYLE 5 25, 27, The exercise. variance a Find 4 this numbers. 9, of for of in words a year of 29 children deviation. that the group. students Find the Pafnuty Lvovich (1821–94) Russian 10–14 11 15–19 10 was 20–24 20 25–29 10 how standard 30–34 12 35–39 6 40–44 3 1 50–54 1 theorem the value deviation applied to Several statistical advances Russia 19th 45–49 a mathematician. Chebyshev’ s shows Chebyshev wish any were and can Y ou research a be set. made France centur y. to data of in in the may some more. 55–59 2 60–64 3 65–69 0 70–74 1 75–79 1 Chapter 6 A sur vey 208 was randomly chosen of bedrooms Number of houses whether the 41 60 52 32 15 8 mean c Write down the standard EXAM-STYLE A random used to using per (t is discrete number of or table. continuous. bedrooms deviation the of the per house. number of house. many houses standard have deviation a number above the of bedrooms greater mean. QUESTIONS sample collect their T ime in 6 the how shown 5 down one are in 4 Write than results bedrooms 3 b Find The of 2 State d data number 1 a per the of houses. Number bedrooms 7 conducted of data 167 on phones. people the The who amount results are own of time mobile they displayed in phones spent the per was day table. spent day 0 ≤ t < 15 15 ≤ t < 30 30 ≤ t < 45 45 ≤ t < 60 60 ≤ t < 75 75 ≤ t < 90 minutes) Number of 21 32 35 41 27 11 people Use your values day 8 in of on The graphic the these figure the net display mean below of and mobile a standard to calculate deviation of approximate the time spent per phones. shows small calculator the lengths in centimetres of fish found trawler. 12 10 hs 8 fo rebmuN 6 4 2 0 20 40 60 80 100 120 Length (cm) a Find the b Write c i total down Write number an of estimate down an fish of estimate in the for the net. mean the length. standard deviation of the lengths. ii How many fish (if any) have length greater than three Extension material Worksheet 8 central standard deviations Descriptive statistics above the mean? - on CD: Measures tendency and of spread Investigation – the eect of multiplying adding the or data set on a standard deviation Here is a set a Calculate b Now add 100, Calculate d Explain e Now the to What 4, 0, all g What the will Eect to the 10, the to constant in k standard but If the you a list, 5, 5, these in the 101, 104, deviation and of why values 10, 1, 4, 6 numbers. series: to get 104, 102, 106. 2, in 8, this this the new set. happens. original list by 2 to 12. mean? deviation. the variance? changes a add/subtract numbers 3, mean? standard happen of you of 9, of notice 6, 0, numbers 105, the standard 18, 2, deviation the 105, to happens Calculate all you multiply 8, 4, standard 103, what f If the happens c ➔ numbers: 100 109, What get of the to Why? the constant value arithmetic deviation multiply/divide all original mean remains the k to/from all may to use in your be expected these rules the increases/decreases the numbers Y ou data: exam. See by question 3 non-GDC review in the same in the list by a exercise. constant value deviation Review are k, both the arithmetic multiplied/divided by mean and the standard k exercise ✗ 1 2 Find a of 7, A 1, the class home 8, mode, 2, 6, collected as shown b the 5, the in median, 10, data the c the mean on table the number 3 4 5 6 7 8 9 10 f 3 9 10 2 3 1 1 0 1 a Calculate the mean b Calculate the median. c Write The 17.5 mean years again and at the the d range of pets in their below . 2 down and 3 Pets EXAM-STYLE 3 3, number of pets. mode. QUESTION age and the of a the group standard school standard of reunion deviation of friends at deviation after their 10 the is end 0.4 years. of school years. What is They the is all new meet mean ages? Chapter EXAM-STYLE 4 A farmer results QUESTIONS grows are two shown different 45 Type 50 Mass Find 5 The the a of is six 92 sweetcor n and the season’s B 60 grams median, mean another 55 in of below . Type A 40 types b the range, numbers and the is other c 71. four the interquar tile One number numbers are is range for each Y ou could type. 46, all be asked to calculate the the mean using the formula or a GDC. Y ou same. will Find a the total of all six numbers. b a If c each find 6 the Draw a of a the six mean of numbers the cumulative new is set decreased of frequency only be standard by expected deviation or to calculate variance GDC. 9 numbers. graph for the data in the table. ‘Estimate Height 150 ≤ h < 155 155 ≤ h < 160 160 ≤ h < 165 165 ≤ h < 170 170 ≤ h < 175 graph’ you (cm) f 4 22 56 32 5 Estimate the median from c Estimate the interquar tile your A dice and is six rolled written The following Number Frequency a Calculate b Find 100 on times. from dice your has a number shows the frequencies for 1 2 3 4 5 6 26 10 20 k 29 11 the i graph. between it. table value of each number. k the median the midday ii the interquar tile range. o 8 The table gives mountains in November. Temperature 12.5 ≤ t < 27.5 6 27.5 ≤ t < 42.5 3 42.5 ≤ t < 57.5 5 57.5 ≤ t < 72.5 8 72.5 ≤ t < 87.5 6 102.5 2 87.5 f ≤ t < Descriptive statistics temperature Find the as ( F) median in and the Omani IQR. one your that show and graph. the ver tical working graph. range Each means horizontal your 7 from should lines b the using on Review 1 Calculate 9, 11, the 12, 13, EXAM-STYLE 2 June for 3 r uns last exercise median 13, 17, and 19, interquar tile 21, 21, 25, 27, a cats’ year 33, 35 home. The numbers of kittens per litter were 4 5 6 7 8 9 f 3 7 11 12 6 3 a Find the mean b Find the standard numbers season 30, of QUESTION Kittens The range of number of kittens per litter. deviation. tennis racquets broken by 410 players in a were. Broken 2 3 4 5 6 7 8 9 10 3 11 43 90 172 13 64 10 4 racquets f Find EXAM-STYLE 4 The the a in the b median the of hours students study mathematics 0 1 2 3 4 5 6 f 2 5 4 3 4 2 1 Find the mean. the each night is table. Hours a c QUESTION number given mode mean, median, mode, standard deviation and variance. Find b 5 The the range, histogram school in lower below quar tile shows the and the heights interquar tile of the range. students in a high Per u. y 90 80 70 ycneuqerF 60 50 40 30 20 10 0 140 150 160 Height a Write b Constr uct for down the a the 170 modal grouped mean 180 190 x (cm) height class height. frequency of the table Per uvian and calculate an estimate students. Chapter EXAM-STYLE 6 A school words the QUESTION with they table 150 can remember in of Cumulative of 11 16 21 32 17 33 p 18 q 19 38 137 20 13 150 Write down the Find the median Find the mean CHAPTER 8 Univariate ● Univariate ● Data is either value the of number number information quali tative data data can that or be a Find ii single you split the value of q variable. gather up into and is classified as data. two categories: discrete continuous. discrete continuous depends on the Continuous have statistics, par t of or the group the you groups in term to a the as exact can numerical be measured measuring length, values. and instr ument weight and time, its accuracy used. may population we are includes studying is selection called of for a all data sample. individuals members driven It is from a of a decisions. subset the of population. data a lot grouped continuous similar a have a of such population Presenting has variable decimals. that population, When variable accuracy variables, fractions defined the number quanti tative quantitative For in words. involves quantitative ● given analysis A ● are SUMMARY A the results French words. ● A p of of ● ● The many 99 analysis Quantitative and how students 11 c In see 15 b ● to minute. students i ● tested one Number words a ● is below . Number of students bar of data, you frequency data, char t you but can it can organize it into table. draw doesn’t a histogram. have gaps It is between bars. Continued Descriptive statistics on next page Measures of central ● The mode is the value ● The mean is the sum of numbers in a set of of Sum of Mean that The number the ● If in of mean there the most numbers frequently divided by in the a set of data. number data. = is median numbers occurs the data values Number of ● tendency a the set number of data numbers of are the a in two lot data values of present are a in the arranged data middle set is in middle order even, when of then size. the the If the median is numbers. numbers and it is difficult to find the middle ⎛ n +1 ⎞ member we can use the formula Median = th ⎜ where n is the number of members in the member, ⎟ 2 ⎝ ⎠ set. Advantages ● Mode The be mode used can when choose do not affect the ● asked Does of data the popular values mode. for qualitative or Extreme Disadvantages ● Not – to not the use data all necessarily may be members set. more unique than one answer . ● most item. When the no data values set, repeat there is in no mode. ● When one there mode, interpret ● Mean The mean describes middle of of Most such the a set data. popular as computer ● Uses ● It is measure business, all in ● elds engineering and Affected is it more is and/or by than difcult to compare. extreme values. science. members unique – of there is the data only set. one answer . ● Useful when comparing sets of data. ● Median The median describes middle of of median the a Extreme set values as do strongly not as affect they the do the mean. ● data. Useful ● Not ● Less as popular used in as mean. fur ther calculations. when comparing sets of data. ● It is unique – there is only one answer . ● As the 50% of median the is data the is middle either value, side of it. Continued on next Chapter page Measures ● The is range F irst of dispersion the difference quar tile The of between first the data lies into the below lies percentile the data. the above. and largest is quartile way four ths the rst It often is and value One has and called the values. one-quar ter quar ter quar tile also smallest of three- the symbol the 25th Q 1 Second quar tile The the second median also Third quar tile The way the It called third in. is of the the also the called set of name data for and three-quar ters of and the symbol another is percentile. is quarti le quar tile is entire 50th Three-four ths third has quarti le the data lies one-four th 75th lies percentile of the below above. and Q 3 3 1 Q = (n + 1)th value and Q 1 = (n number The the ● A 1)th value where n is the 4 4 ● + 3 of data difference values between interquarti le five box statistical and in the the data third set. and first quar tiles is called (IQR). range summary can be represented graphically as a plot. whisker Range Whisker Min Interquartile Q X Range Whisker m Max Q 1 X 3 (Median) ● An outlier is any value at least 1.5 IQR above Q or below 3 Cumulative ● To of calculate the data Variance ● The a the differences cumulative values of as you go frequency spread. between It all is each add up the frequencies along. standard combines variance 1 frequency and measure Q the the deviation values in arithmetic value and the a data mean mean set of to the produce squared value. Continued Descriptive statistics on next page ● The has ● standard the The same deviation units formulae for as the is the the square root of the variance and data. variance and standard deviation are: n 2 2 σ = Population variance x = i 1 n n 2 σ = Population standard deviation x = i 1 n Eect of If you add/subtract in a list, the standard If you value are constant changes a arithmetic deviation both the mean all by original value k data: to/from all increases/decreases the the arithmetic multiplied/divided the constant remains multiply/divide k, to the by k numbers but the same . numbers mean and in the the list by standard a constant deviation k Theory of knowledge Facts in and statistics Statistics as F ind out what misconceptions it What Is What main how led did it its a relatively advances Florence moder n have Nightingale branch been used made of in statistics mathematics the past and to. Francis easy is is to Galton mix the up μ invent? and difference x ? between a sample and a population? Do different median, Were mode) measures discovered? measures Could of express of central different central Where do mathematics (mean, proper ties tendency they make tendency come of invented the or from? alter native, equally tr ue formulae? What Darrell 1954) does Huff's this book attempted spin-doctors “Statistical efficient for What Do of How to to you you agree knowledge: will as G. mathematical with the Wells with and one the think Facts Lie expose thinking do about Statistics tricks ‘self-defense’ citizenship Theory us the H. tell of day ability of the ‘honest be to as (Nor ton, statistical men’. necessar y read and (1866–1946) H. G. Wells meant? him? misconceptions in tr uths? statistics for write.” data? 400 years. How easy Criticize these is it to lie with statistics? graphs: 4.8% 3.3% We so are much now 3.1% b etter than were 3.1% doing in we “There kinds 1990s 1970s 1980s 1990s ease incr lies: 40 author Mark in lies, statistics.” US huge of damned and a three Current lies, t Wha are the Twain attributed this to 30 the b er num of the 19th British s frog Minister, century Prime Benjamin Disraeli 0 May Take their a sur vey favorite Use of your style situation friends about Here subject. Microsoft different September (or you Excel char ts draw to to show the by hand). Tr y the changing value Show the 3D the y-axis y-axis scale star ts some use, of the and ‘tricks’ how that they mislead: produce graphs are could Showing or hides or of data. highlights the large or This change repor ted. Using a nonlinear expecting char ts. unsuitably amount being at. an small a linear scale. scale Anyone would be misled. See what happens to a subject that may have zero votes on a pie Not Keep char t. also can can be be ver y used ■ How can ■ How can to distor t statistics we helpful be decide in our used providing an them Making the scale at all. uninformed. bars of a histogram three-dimensional. It difference data look Statistics showing between makes the values larger. influential inter pretation of reality but perceptions. or whether misused to accept to the assist and statistical mislead evidence us? that is presented to us? Chapter Integration CHAPTER OBJECTIVES: 1 n Indenite 6.4 integration as antidifferentiation. Indenite integral of x (n ∈ ), x x and e . The Integration composites by Denite the revolution 1 you should Write a a. the any or of these with substitution boundar y analytically the of the the condition and x-axis). to using Areas linear form function technolog y. the of given terms. Areas cur ves. under Volumes T otal displacement distance s, velocity v of and how in Skills to: sigma notation as a 1 check Write as a sum of terms. 6 e.g. 2 (2i ) b i 1 1) cur ves traveled. a (2i term. x-axis. involving 4 b constant 5 sum + f (g(x))g′(x) dx determine between ax start know series a and problems acceleration Before both cur ve about Kinematic 6.6 with integrals, (between Y ou inspection, Antidifferentiation 6.5 of (3k 2) k 2 [2(2) 1] [2(3) 1] [2( 4 ) 1] 5 i 2 3 2 c 5 7 9 [(i ) g(x )] i d [ f (x )( x j )] j i 1 j 1 4 e.g. f (x ) = f (x j ) + f (x 1 ) + (x f 2 ) + f (x 3 ) 4 2 Find the area. j =1 a 2 Use geometric formulae to find area. b 5 mm 4 mm e.g. Area of trapezium: 7 cm 9 mm 1 = (b + b 1 8 cm )h 2 2 3 10 cm Find the volume. 1 8 cm = (10 + 8)( 6 ) a b 4 m 2 2 = 54 cm 6 cm 14 ft 10 cm 3 Use geometric formulae e.g. to Volume find of volume. sphere: 2 m 4 r 3 Integration 32 4 3 V 3 (2) 3 3 m 3 6 ft We know we derivative on the Can a find the Suppose find the find the of a moving function function). Now object (carr ying consider function for out the a by taking the differentiation reverse moving process. object, if you function? velocity function, velocity displacement velocity the the displacement displacement you know of can s (t) function such that is given s ′(t) = by v (t) 2t +1. = 2t + 1. Working We need backwards, differentiation to we 2 t + t 2t + 1 2 find one possible displacement function is s (t) = t + t + t, since integration d 2 (t 2 t ) 2t 1. Why do we say that s (t) = t is one possible dt displacement function? 2 The function The process chapter you integration line, . area s (t) of t +t finding will can and = lear n be is an called to the solve the of problems v (t) = 2t called integration. is process of integration involving and motion + In 1. this how on a volume. Antiderivatives Suppose antiderivative antiderivative about used an derivative of a and the function f is indefinite given by 2x +3. integral Working 2 backwards, we find that f may be the function f (x) = + x 3x, since d 2 (x 3x ) 2x 3. But there are other functions that have the same dx 2 2 derivative, such as f (x) = x x 2 + 3x + 1 or f (x) = x + 3x – 6 + 3x + + 3x – + 3x 1 since 2 x d d 6 2x + 3 2 2 (x 3x 1) 2x 3 (x and 3x 6) 2x 3 2 dx dx x Chapter 2 The are functions all called f (x) = 2 x + 3x, f antiderivatives (x) of = 2x 2 x + + 3x + 1 and f (x) = x + 3x – 6 3. A 2 Any function of the form f (x) = x + 3x + C, where C is an an arbitrar y f constant, is an antiderivative of 2x + function F is called antiderivative if F ′ (x) = of f (x). 3. n Investigation Copy and – complete f (x) antiderivatives of the table Antiderivative of below. The rst x entr y is completed for you. f 1 2 x x C 2 2 x 3 x 4 x n Write a Show Are general expression or r ule for the antiderivatives of x 1 2 –3 whether there any your r ule values of gives n the where correct your antiderivatives rule does not for x and x apply? 1 n +1 n The antiderivatives of x are given by x Just C, + as the process of n + 1 nding where C is an arbitrar y constant and n ≠ –1. is a derivative called dierentiation, Example the an Find the antiderivative of each process of nding antiderivative is called function. antidierentiation. 1 4 10 a x b c 3 x 5 x Answers 1 1 10 +1 x a 1 11 +C = 10 + 1 n +1 x +C Apply the rule 11 n where n = + C , x + 1 10. 1 5 = b Rewrite using rational exponents. x 5 x 1 n +1 Apply 1 the rule + C , x 1 −5 +1 x −4 +C = x −5 + 1 n +C 4 where 1 n = + 1 –5. Simplify. = +C 4 4 x 3 4 c 3 x 4 = Rewrite x using rational exponents. 1 n +1 3 1 7 1 1 = x x + C , Remember 1 n + 1 2 7 x x x x x x 3 1 4 rule +C where the 4 +C 3 Apply 4 x 4 n = 1 4 3 3 7 4 1 4 = x 7 Integration +C Simplify. 4 4 etc. Exercise Find the 9A antiderivative of each function. 1 7 4 x 1 –2 x 2 1 2 x 3 x 4 2 1 1 3 5 x 5 x 6 7 8 12 4 x x 1 7 3 x 9 1 3 x 10 11 12 5 3 x Antidifferentiation is also known 2 x as indefini te integration and is If denoted with an integral symbol, dx. For F ′(x) = f (x), we write example, f (x) dx = F (x) + C 1 3 x 4 dx = x + C 4 The expression 1 3 means that the indefinite integral (or antiderivative) of 4 x is x + C. f (x) dx is called an 4 indefini te These r ules will help you find indefinite f (x) dx ➔ Power integral. integrals. is read as rule ‘the n antiderivative of n+1 x dx = x + C, n ≠ 1 f with respect to x’ or n 1 ‘the ➔ Constant integral ➔ = kx Constant + C (x) dx multiple = k f to Sum or x’. rule = F (x) + C (x) dx Integrand ➔ with Variable f (x) dx kf f rule respect k dx of dierence Constant rule of ( f (x) ± g (x)) dx = f (x) dx ± g (x) dx integration Example Find the indefinite integral. 6 a x 5 dx 4 d (3u 4 dt b c 3x e (x dx 2 + 3 6u + 2) du + x ) dx Answers 1 6 a x 6+1 dx = x + C Apply the power rule Apply the constant with n = 6. 6 + 1 1 7 = x + C 7 b 4 dt = 4t + C variable of rule. The integration is dt tells you that the t. { Continued on next Chapter page 5 5 3x c dx = 3 x ⎛ dx Apply the Apply the constant multiple rule. ⎞ 1 5 +1 = 3 x ⎜ +C 5 +1 ⎝ power rule with n = 5. ⎟ 1 ⎠ 1 6 = x + 3C 3C 1 is some arbitrar y constant C. We usually just 1 2 show the final arbitrar y constant. 1 6 = x + C 2 4 2 (3u d + 6u + 4 = 3u 3 = 3 u ⎛ + du + 6u du + 2 du sum rule. du + 2 du Apply the constant Apply the power 2 6 u ⎛ ⎞ 1 u ⎜ rule and rule. constant rule, with 2 +1 + ⎟ 4 + 1 multiple ⎞ 1 4 +1 ⎝ the 2 du 4 = Apply 2) du 6 u ⎜ ⎟ 2 + 1 ⎝ ⎠ + 2u + variable C of integration u. ⎠ 3 5 = 3 u + 2u + 2u + We C actually get a constant of integration for each 5 ter m, but C + C 1 + C 2 is some arbitrar y constant C. 3 1 3 (x e 1 + x ) dx = (x + 3 ) dx x Rewrite using rational exponents. 1 1 +1 1 1+1 = x 3 + x + C Apply the power rule to each ter m. 1 1 + 1 + 1 3 4 1 3 2 = x 3 + 2 Exercise Find the x +C 4 9B indefinite integral in questions 1 to 10. Y ou can check the 1 3 1 x dx answers dt 2 to your 2 t indenite 4 5 x 3 dx 4 answer to 2 (3x + 2x + 1) dx by your 2 du 4 5 integrals differentiating see and that checking it equals dx 6 3 x (t 3 4 2 7 the + t ) dt 8 ( integrand. 2 x + 1) dx 0 dt 4 9 (5x 3 + 12x + 6x – 2) dx 10 4 3 11 Let f (x) = x + . 2 x Find f a ′(x) b f (x) dx 5 12 Let g(x) Find a Integration = 30 x g ′(x) . b g (x) dx dt = 1 × dt = t dt Y ou saw moving at the object beginning is given of by this v (t) = section 2t + 1, that then if the the velocity of a displacement of the 2 par ticle is s(t) = + t t + C, for some arbitrar y constant 2 now the write this general Suppose time t = (2t solution you 1 as is are 6. 1) dt for also Y ou + (2t given can = + t Y ou can 2 + t + C, where t + t + C is called 1) dt. that, then C. for find this par ticle, the position at at = C 2 s (t) = t + t + C 2 + s (1) = 1 6 = 2 C = 4 + 1 + C C 2 Therefore, s (t) = + t t + 4. The fact that the position time t 1 is 2 6 is called a boundary of solution (2t Example + 1) condi tion dt, given and the t + t + 4 boundar y is a particular condition. 2 a If f ′(x) b The = 3x + 2x and f (2) = –3, find f Sometimes (x). boundar y cur ve y = f (x) passes through the point (32, 30). The the cur ve is given by f ′(x) is = condition gradient 1 of a given as an ini tial . 5 3 condi tion. This represents a x Find the equation of the cur ve. condition dP The c rate of growth of a population of fish is given by = 150 t when t is zero. For dt example, for 0 ≤ t ≤ 5 years. The initial population was 200 fish. Find of fish at t = 4 you are the told number if that the initial years. displacement 4, this means is that Answers displacement is 4 2 f a ′(x) = 3x + 2x when t = 0. 2 f (x) = (3x + 2x) dx Apply the power rule to find the 2 3 f (x) = x x + 2 3 f (2) 3 C = = 2 8 f + = (x) = + C + C (3x + 2x) dx. 2 4 + Use the fact that f (2) = –3 to find C. C 15 3 ∴ general solution for 2 + x 2 + x – 15 1 b f ′(x) = 5 3 x 1 f (x) = dx 5 Rewrite with rational exponents 3 x and 3 5 = x apply the power rule to find the 1 dx general solution dx for 5 2 3 x 5 5 f (x) x = + C 2 { Continued on next page Chapter 2 5 5 f (32) 30 (32 ) = = C 10 = + + C Use the fact that through the Rewrite with the point cur ve (32, 30) passes to find C. C 20 2 5 5 ∴ f (x) = + x 20 dP = c 150 t dt P(t) = t dt 150 and find the rational general exponents solution for 1 t 150 t 150 2 = dt dt 3 2 P(t) = 100t + C 3 2 P(0) = 100 ( 0 ) 200 = 0 + C = 200 + The C initial means C population P(0) = 200. was Use 200 this to fish find C. 3 2 P(t) 100t = + 200 3 2 P(4) = 100 ( 4 ) = There t = 4 + Find 200 P when t is 4. 1000 are 1000 fish when years. Exercise 9C Exam-Style Questions 5 1 The derivative The graph Find an of f of the function f passes expression is through for f given the by point f ′(x) = 4x + 8x. (0, 8). (x). dy 4 4 2 It is given that = x + of a x and that y = 10 when x = 1. dx Find y in terms of x. –1 3 The velocity v m s , moving object at time t seconds is given 2 by v (t) When Find = t = an – 3t 3, 2t. the displacement, expression for s in s, terms of of the object is 12 metres. t 3 4 The rate at which the volume of a sphere is increasing in cm dV 2 is given by = 2π (4t + 4t + 1), for 0 ≤ t dt 3 volume Find was the Integration π cm volume of the sphere when t = 3. ≤ 12. The initial –1 s Exam-Style Question –1 The 5 velocity by v (t) = a Find b The 20 v m s – of a moving object at time t seconds is given 5t –2 its initial Find . The acceleration an More power m s displacement expression on r ule in for s s is in integration metres. terms indefini te for 5 of t. integrals tells us that Why do we say that 1 n x n+1 dx = x + C, n ≠ −1. The r ule does not work 1 when is n + 1 undened? 0 –1 n = –1 because it would result in dividing by 0. So what is x dx? 1 0 Is the same as 1 –1 Y ou have seen ? 0 0 d (ln x) that dx = = x for x > 0, Why so or why not? x 1 ➔ dx = ln x + C, x > 0 x d x Also (e x ) = e , so dx x ➔ e x dx = Example Find the e + C indefinite integral. t 4 e dx a dt b x 2 Answers ⌠ a 4 ⌡ 1 ⌠ dx ⎮ = 4 ⌡ x Apply dx ⎮ the constant multiple rule. x 1 = 4ln x + C, x > 0 Use the fact that dx = ln x + C, x x > 0. Integration rules t e 1 t b dt e = Apply dt the constant multiple rule. 1 dx 2 = ln x + C, x > 0 2 x x Use 1 the fact that e x dx = e + C. t = e + C x e x dx = e + C 2 2 3x 2 For some integrals such as (x + 2x + 1 2 + 1) dx dx, x 2t–1 and ln (e expanding you can ) dt the you may bracket, integrate. The have to rewrite separating next the example the terms shows integrand or by simplifying before how . Chapter Example Find the indefinite integral. 2 3x 2 (x a + 2x + 1 2 + 1) 2t–1 dx dx b ln(e c ) dt x Answers 2 2 (x a + 1) 4 dx = 2 (x + 2x Expand + 1) dx and then integrate each ter m. 1 2 5 = x 3 + x 5 + x + C 3 2 3x + 2x + 1 b dx x 2 ⎛ 3x 2x = + x ⎝ ⎮ ⎜ x 1 3x ⎟ x ⌠ ⎛ = ⎞ 1 + ⎜ dx Separate the ter ms. Simplify and ⎠ ⎞ + 2 + dx then integrate each ⎟ x ⌡ ⎝ ⎠ ter m. 3 2 x = + 2x + ln x + C, x > 0 2 2t–1 ln(e c x ) dx = (2t – 1) dx Simplify 2 = Exercise Find the t – t + ln x C are using the fact that e and inverses. 9D indefinite integral. 2 x 1 dx 2 3e dt 4 e dx x 1 ln x 3 dx 4t 3 2x 2 6x 5 2 (2x 5 + 3) dx 6 dx x 2 u ln 7 3 e du 8 dx 10 (x x e – 1) dx 2 1 9 x + x + 1 dx 2 x Y ou can rule Now we look at indefinite integrals of functions that with the linear function ax + verify right-hand the equation showing 1 + b) that and you get 1 n 1 n (ax side b of ➔ each differentiating are the compositions by dx = ( ax a + b) C the integrand. n 1 1 ax + b e ➔ ax + b dx e = + C Note that ln(ax + b) a is 1 ⌠ ➔ 1 dx ⎮ + b) + C , x > ax + b a when b − ax ⌡ dened b ln( ax = + b > 0 or x > – a a Integration Example Integration Find the indefinite rules integral. n (ax a (3x + 1) 2x+5 dx e b dx + b) dx = 1 3 4 dx c dx d 4 4 x (6 x 2 + 3) 1 1 n1 ( ax a Answers 1 ⎛ + b C + 1) ( ax Find dx = e + 1 5 = (3 x ⎟ 1 + 1 n ⎝ ⎠ + ⎜ 3 ⎝ ax ⎞ + 1) for C a = 3, b = 1 and n = = b 4. ⎟ 5 1 ⎠ ln(ax 1 Check 5 = C C dx 1 ⎛ + a + b ) ⎜ a ax + b dx ⎞ n +1 4 (3x + b) 1 ax e 1 a n 1 (3 x + + 1) by x d 1 ⎡ 5 1 ⎤ dx ⎣ + C (5(3x + 1) > – a 4 = (3 x + 1) ⎢ b) b C 15 + a dif ferentiating. (3)) ⎥ 15 15 ⎦ 4 = 1 1 2 x +5 b e 2 x +5 dx = e + 1) ax + b Find e + C (3x + C for a = 2 and b = 5. a 2 Check d by ⎡ 1 dif ferentiating. 2x + 5 dx dx 4 x = 2 ⎣ [e 2x + 5 = (2) ] e 2 ⎦ Apply dx 3 4 x 2 the Find − 2) ⎢ + C , x rule. Check 3 d 1 4 x by dif ferentiating. 2 ⎦ ( ln(ax + b) for a = 4 and b = –2. > ⎥ 4 ln multiple a 1 ⎤ ln( 4 x ⎣ constant 2 1 ⎡ 1 3 = 2x +5 = ⎥ 1 3 c = 1 ⎤ e ⎢ − 2) + C , x ⎡ 3 2) ⎢ 4 dx 2 ⎣ 3 ⎤ ln(4x > 4 1 ⎛ ⎞ = (4) ⎜ ⎥ 4 ⎦ ⎝ ⎟ 4x 2 ⎠ 3 = 4x 2 1 –4 d 4 (6 x dx = (6x + 3) dx Rewrite using rational exponents. + 3) 1 1 ⎛ n +1 Find 1 ⎛ 1 3 = (6 x + 3) ⎜ 6 ⎝ a + C ⎝ ⎞ + b ) + C ⎟ n + 1 ⎠ ⎟ 3 ⎠ for a = Check 1 = ( ax ⎜ ⎞ − + 6, by b = 3 and n = – 4. dif ferentiating. C 3 18( 6 x + 3) d 1 ⎡ = 3 − (6x d ⎡ dx ⎣ ⎤ 1 ⎢ 3 18( 6 x + 3) dx ⎣ ⎤ + 3) ⎢ ⎥ 18 ⎦ ⎥ 1 1 ⎦ 4 = − ( −3(6x + 3) (6)) = 4 18 (6x + 3) Chapter Exercise Find the 9E indefinite integral in questions 1–10. 1 x 2 (2x 1 + 3 5) dx (–3x 2 1 + 5) 3 2 dx dx 3 e 6 4e 3 2x+1 dx 4 5x dx 5 + 4 7 dx 2x 1 ⎛ – 3) dx ( 8 7x + 2 ) dx 9 ⎜ 4 4 x 2 7 6(4x 7 e ⎞ + ⎟ dx 3x ⎝ 5 ⎠ 2 10 3 3( 4 x dx 5) Exam-Style Questions 3 Given 11 f a that f (x) = ′(x); (4x f b + 5) find (x) dx. –3t 12 The velocity The displacement metres The We f v when of t a = use of 0 substitution par ticle the at par ticle seconds, g ′(x) dx. Example Find the a (3x The t at express is given time t s in is by s. terms v (t) = Given of e + that s 6t. = 4 t method the substi tution method (g (x)) time next to example evaluate shows integrals you of the form how . indefinite integral. 3 2 4 + 5x) (6x + 5) dx b 2 x 3x 3 12 x (2x – 3) dx 2 3x 2 4 x c +1 x e dx d 4 3x 3 dx x Answers 2 a (3x 4 + 5x) (6x + This 5) dx f integral (g(x)) is of the for m g′(x) dx, 2 where g(x) = 3x + 5x and g′(x) = 6x + 5. du 4 4 u = dx = u du du 2 Let u = 3x + 5x, then = 6x + 5 and substitute. dx dx 1 Simplify and integrate. 5 = u + C 5 2 1 Substitute 2 = (3x 3x + 5x for u. 5 + 5x) + C 5 { Integration Continued on next page Check by dif ferentiating. ⎡ 1 d 2 5 (3 x dx ⎣ ⎤ + 5x ) ⎢ ⎥ 5 ⎦ 1 2 = 4 (5(3x + 5x) (6x + 5)) 5 2 = 3 (3x + 5x) (6x + 5) 2 x b 4 3x (2x – 3) dx This f integral (g(x)) is of the for m g′(x) dx, 2 where g(x) = x – 3x and g′(x) = 2x – 3. 1 du du 2 3 = u dx Let u = x – 3x, then = 2x – 3 and substitute. dx dx 1 = 3 u du Simplify and integrate. 4 3 3 = u + C 4 4 3 2 = (x 2 3 − 3x ) + C Substitute x – 3x for u. 4 Check by dif ferentiating. 1 4 ⎡ d ⎤ 3 2 ⎢ dx 3 ⎛ ⎞ 4 2 3 (x 3 x ) = ⎥ 4 ⎜ 4 ⎣ (x ⎦ 3 − 3 x ) (2 x − 3) ⎟ 3 ⎝ ⎠ 1 ⌠ ⎛ 1 2 4 x c +1 x e dx = ⌡ ⎝ ⎞ × ⎮ ⎜ 8x 3 (x – 3x) (2x – 3) x = 3 x (2x – 3) 2 4 x +1 e 2 d ⎟ 8 2 3 2 = If g(x) = + 4x 1 then g ′(x) = 8x. Rewrite the ⎠ 2 1 4 x integrand +1 e = ( 8x ) so that it is in the for m c f (g(x))g ′(x) dx. dx 8 du u 1 du e dx 2 = Let u = 4x + 1, then = 8x and substitute. dx dx 8 1 u e = du Simplify and integrate. 8 1 u e = + C 8 2 1 4 x +1 e = 2 + C Substitute 4x + 1 for u. 8 3 2 12 x 3x dx d 4 3 3x This integral is of the for m x 3 du 2 12 x f (g(x))g′(x) dx, where 3x dx 4 = dx dx 3 3x 4 x g(x) = 3x 3 – x 3 and g(x) = 12x 2 – 3x u 1 = du du 4 Let u u = 3x 3 − x , 3 then = 12x 2 −3x dx = lnu = ln(3x + C, u > 0 and 4 4 3x x ) x + C, Simplify 3 – substitute. 3 – > and integrate. 0 4 Substitute 3x 3 – x for u. Chapter With f practice (g(x))g ′(x) dx about of f you u what is the with the factor to be able inspection. would other Exercise Find by you respect may the indefinite That choose of find for is, u, you may check integrand integrals to and just see be that then of the able the form to think derivative mentally integrate u 9F indefinite integral in questions 1–10. 2 3x 2 + 2 2 (2x 1 + 5) (4x) dx dx 2 3 x + 2x 4 3 2 (6x 3 + 5) 3x 5x 4x 4 dx x e dx x 2x 3 e dx 5 2 (x 3x 2 x 7 dx 6 2 1) 3 2 2x 4 (2x + x 5) dx 1 8 dx 4 2 x x 2 4 3 4 (8x 9 – 2 4 x)(x – x 3x 3 ) dx dx 10 3 x Exam-Style 4 x Questions 8x Let 11 f ′(x) = . 2 4 x Given that f ′(0) = 4, find f (x). + 1 3 2 The 12 gradient passes . This of through Area section and is a cur ve the is point given (1, 5e). defini te about the by f ′(x) Find = an 3x x e . The expression cur ve for f (x). Indenite integrals functions that are a family a constant. of integrals definite integral, Denite differ integrals by are real numbers. b In which is written as f (x) dx, and its relationship the next section we will learn to about the relationship between a the area under a denite cur ve. how to – area and the definite indenite evaluate without Investigation and a a integrals denite and integral GDC. integral y 5 2 1 Consider the area bounded by the function f (x) = x + 1, x = 2 0, f(x)= x + 1 4 x = 2 and the x-axis, which is shaded in green in the graph. 3 a i Write down the width of each of the four rectangles shown 2 in the R graph. 4 R 3 ii Calculate the height of each of the four rectangles. R R 2 1 iii F ind the sum of the areas of the four rectangles to nd –0.5 a lower bound of the area of the shaded 0 { Integration 0.5 1 1.5 2 x region. Continued on next page Write this down the width of the four rectangles shown in graph. 5 2 f(x)= ii Calculate iii F ind the the sum height of the of each areas of of the the four four rectangles. rectangles x + 1 4 to nd 3 R 4 an upper bound on the area of the region. 2 R 3 Use c a GDC to evaluate the defini te integral R 2 R 2 1 2 + 1) d x . x Compare your result with your answers x –0.5 0 0.5 1 1.5 2 0 in par ts and a b The What do you think the denite integral might GDC an approximation method GDC help on CD: demonstrations Plus and Casio to are on the the TI-84 values the could Now 2 we not 1; will F ind use we a geometric could only consider the area of use some the formula to nd geometric regions shaded whose region the area formulae area under to can the denite of the region approximate be line so the CD. are question of FX-9860GII values We determine Alternative for integrals, GDCs uses represent? found f(x) = from not the always GDC exact. in the area. geometrically. 2x + 2 y between x = –1 and x = 2 using a geometric formula. Then 6 write down a denite integral you think may represent the area. 4 Evaluate the integral on a GDC and compare answers. x 3 We refer to the area between a function f and the x-axis y the area under the curve . If f(x) is a = 2 2 as = 2x + 2 non-negative 0 –3 function that 4 for gives Verify and it then on the that following a a ≤ ≤ area your by x b then under answer nding writing the down write the down cur ve from question area using a denite a from 3 denite x = a works integral and to for geometric f (x) = – x = + 3 from = 1 to b = 1 x the evaluating = = 5 formula In mathematics, is a coordinate x 4 –4 graph a on plane, a so 4 4 x 3 –2 y x x –1 cur ve 2 x –2 integral GDC. 1 a f the cur ves include lines. 4 2 1 y x + 1 3 2 x –1 0 2 b f (x) = 16 x y from x = –4 5 to x = 4 2 y = √16 – x 3 2 1 x –4 –3 –2 –1 0 1 2 3 4 Chapter In the investigation you approximated the area under a Approximations for area under 2 cur ve areas f (x) of = x four + 1 from rectangles. x = 0 to Using x = 2 sigma by summing notation, we 2 the f(x) can = x + different 1 from x numbers = 0 of to x = 2 for rectangle. 4 Upper # express this ∑ as f (x )Δ x , i where f (x ) i represents Rectangles Lower sum the sum i i =1 4 height of each rectangle and represents Δ x the width To 5.75 of i each 3.75 10 4.28 5.08 50 4.5872 4.7472 100 4.6268 4.7068 4.658 67 4.674 67 rectangle. get better approximations of the area we can use 500 more rectangles. Using an infinite number of rectangles, Exact n area = 2 lim ∑ n →∞ 14 f (x )Δ x , i leads to the exact 2 area. (x + 1) dx = ≈ 4.66667 i i =1 3 0 n If a function f is defined for a ≤ x ≤ b and lim ∑ f (x )Δx i Notice that both the lower and upper i n →∞ i =1 sums exists, We we call say this that limit f is the on integrable defini te a ≤ integral x ≤ and appear to approach 4.66667. b. denote it b b n The as lim f ∑ (x )Δ x i n →∞ = f (x) dx or y dx. The number a symbol is an is i elongated S and is i =1 a a also called the lower called the upper limi t of integration and the number b When f is a non-negative sum. The a ≤ x ≤ b, German f denite notation introduced y function b for indicate integration. integral ➔ to is a of limi t used (x) dx gives y the = by was the mathematician f(x) Gottfried Wilhelm a Leibniz towards the b area under the cur ve from ∫ f(x)dx a end x = a to x = of the b 17th b a 0 x b centur y . f(x) dx is a Example Write GDC. as from a a definite Whenever a integral possible find that the gives area the area using a the shaded geometric region formula to and evaluate verify your b to it integral of f (x) with x’. using a answer. y b y of ‘the to respect down read 3 2 f(x) = 2 1 + x 2 1 f(x) = 2 – |x| 1 x –3 –2 –1 1 0 2 Answers –2 –1 0 1 2 x 3 The function intersects the 2 x-axis (2 a –|x|) dx = at –2 and 2 and for ms 4 a triangle. So the limits of –2 1 Area = integration (4 2 × 2) = are –2 and 2. The 4 area for mula for a 1 triangle is A = (b × h ) 2 { Integration Continued on next page The 1 region is bounded by the 2 dx b ≈ 3.14 2 2 1 + function x f (x ) = , the 2 –1 1 x-axis x GDC help on CD: demonstrations Plus and Casio = are on the and x x ver tical = 1. So lines the Alternative for the limits TI-84 of integration are –1 FX-9860GII and GDCs and –1 + the 1. The area cannot be CD. deter mined from a geometric for mula. Exercise Write down region area 9G and using a definite evaluate a integral it using geometric that your formula gives GDC. to the area Where verify your of the shaded possible find the answer. y 4 y 1 f(x) x + = 3 1 2 3 3 f(x) = x – 4x 2 1 1 –3 –1 –1 0 1 2 3 4 5 x 0 3 4 –1 x –2 6 –2 –3 y y 4 4 f(x) = 3 2 f(x) 3 = √9 – x 2 2 1 1 x –2 –1 1 0 2 3 4 0 5 –4 –3 –2 x 1 –1 2 3 4 y y 1 4 3 f(x x + 2 3 3 2 1 f(x) = x 1 1 x 0 –1 1 2 3 –1 x –1 0 1 2 3 4 5 6 7 b When f is a non-negative function for a ≤ x ≤ b, f (x)dx gives y the y = 2x + 2 a area under the cur ve from x = a to x = 6 b 4 Consider what happens when f is not non-negative. –1 2 (2x i + 2) dx –3 –4 The area of the shaded triangle is 4, –3 –2 –1 0 x 1 2 3 –2 but –1 –4 (2x + 2) dx = –4 since f (x) < 0 when –3 < x < –1. –3 Chapter 2 y (2x ii + 2) dx 6 –1 2 4 (2x + 2) dx = 9 is the area of the shaded triangle 2 –1 y since f is a non-negative function for –1 ≤ x ≤ = 2x + 2 2. –4 –3 –2 x 0 –1 1 2 3 –2 2 (2x iii + –4 2) dx –3 2 (2x + 2) dx = 5 because it is equal y y to = 2x + 2 –3 6 –1 2 4 (2x + 2) dx + (2x –3 + 2) dx = – 4 + 9 = 5. This is the –1 2 A 2 negative of the area of the region labeled A plus the 1 area of the region labeled –4 A –3 2 –2 –1 x 0 1 2 3 –2 A 1 This illustrates one b ➔ the proper ties c f (x) dx = (x) dx + a Example graph of definite –4 integrals. b f a The of f (x) dx c of f consists of line segments as shown in the y figure. 8 Evaluate (8, 4) 4 f (x) dx using geometric formulae. 3 0 (2, 2) (3, 2) 2 1 0 x 1 2 –1 –2 –3 –4 (6, –4) Answer 8 f (x) dx = A – A 1 + 2 A Find the area of the trapezium A 3 , minus the area 1 0 the triangle A , plus the area of the triangle, 2 1 = 1 (4 + 1)( 2 ) − 2 2 3 1 (3)( 4 ) + y (1)( 4 ) (8, 4) 2 4 = 5 = 1 – 6 + 2 3 (2, 2) (3, 2) 2 1 A A 1 3 0 x 1 2 –1 A 2 –2 –3 –4 (6, –4) Integration A of ➔ Some properties of b kf defini te integrals b (x) dx = k f a (x) dx a b b (f (x) ± g (x)) dx = b f a (x) dx ± a g (x) dx a a f (x) dx = 0 a b a f (x) dx = – f (x) dx Y ou a do learn b that (x) dx = f (x) dx + f need to a Example go the with these, proper ties. c 2 that 5 f (x) dx = 4, = 2 f 0 4 g(x) dx numbers (x) dx just a the b c f Given not b (x) dx = 12, 2 6, evaluate these g(x) dx = –3 and 0 definite integrals without using your GDC. 0 2 2 2 (3f a (x) – g (x)) dx g (x) dx b 0 + 2 5 f (x) dx 5 4 −1 1 f c (x) dx g (x) dx d f e (x + 3) dx 2 2 0 −3 Answers 2 (3f a (x) –g(x)) dx 0 2 = 2 3f (x) dx – g(x) dx 0 Apply proper ty 2. Apply proper ty 1. 0 2 2 = 3 f (x) dx – g(x) dx 0 0 = 3(4) = 15 – (–3) and evaluate. 2 2 g(x) dx b Substitute + f 2 (x ) dx Apply 5 proper ty 3 to the first ter m and 5 = 0 – f proper ty (x) dx 4 to the second ter m. 2 Substitute = 0 – = –12 and evaluate. 12 5 f c (x) dx 0 5 2 = f (x) dx 4 + = 16 f (x) dx Apply proper ty 5. 2 0 = + 12 Substitute and { evaluate. Continued on next page Chapter 4 2 Apply g(x) dx d + proper ty 5. g(x) dx 2 0 4 = g(x) dx 0 4 So g(x) dx 2 4 2 = g(x) dx – g(x) dx 0 = 6 = 9 Rear range ter ms. 0 – (–3) Substitute and evaluate. –1 1 f e (x + 3) dx Apply proper ty 1. 2 3 The graph of f (x + 3) is a result of –1 1 = f (x + 3) dx translating the graph of f (x) to the 2 3 left 3 units. The limits of integration, 2 1 = f x = 0 x = –3 x = 2 are translated to (x) dx 2 0 1 these = and and x = integrals –1. are So the values of equal. (4) 2 = 2 Exercise ✗ 9H y The graph of f consists of line segments as shown. (6, 4) (8, 4) 4 Evaluate the definite integrals in questions 1 and 2 using 3 geometric formulae. 2 8 1 f 1 (x) dx 4 0 x 1 f 2 (x) dx –2 (3, –2) 0 6 Given that f (x) dx = –3, f –3 6 10 1 (x) dx = 8, g (x) dx = 4, and 1 1 10 g (x) dx = 8 evaluate the definite integrals in questions 6 6 6 1 2 3 f (x ) g(x ) 1 dx 2 g (x) dx 4 10 10 10 g (x) dx 5 f 6 (x) dx 10 1 10 10 f 7 (x) dx f 8 (x – 4 ) dx 5 6 4 10 ( g(x) 9 + 3) dx 3g(x 10 –1 6 2 –1 8 Integration + 2) dx 3–10. Exam-Style Questions 2 Given 11 that 5 h(x) dx = –2 and h(x) dx 0 = 6, deduce the value of 2 5 5 h(x) dx a (h(x) b + 2) dx 2 0 4 Let 12 f be a function such that f (x) dx = 16. 0 4 1 Deduce a the value of f (x) dx 4 0 b b If i f (x ( f – 3) dx = 16, write down the value of a and of b a 4 If ii (x) + k) dx = 28, write down the value of k. 0 . Fundamental Theorem of Calculus y = f(x) y The quotient , the slope of a secant line, gives us an Secant x approximation for the slope of a tangent line line. Tangent The product give us (Δy)(Δx), the area of a rectangle, line helps Δy an approximation for the area under a Δy cur ve. Slope of tangent line ≈ Δx In much are the inverse same sense operations, as division Isaac and Newton multiplication and x 0 Gottfried Δx Leibniz and independently definite This ➔ fact is integrals established Fundamental If f is a came are in the Theorem continuous to realize inverse that following of differentiation operations. theorem. Calculus function on the inter val a ≤ x ≤ b and F is b The an antiderivative of f on a ≤ x ≤ b, notation [F ( x )] a then b means F(b) F(a). b f ( x ) dx = [ F ( x )] = F (b ) − F ( a ). a a 2 2 Consider the definite integral (x + 1) dx that you When applying the Fundamental 0 Theorem evaluated using a GDC in the investigation in Calculus, although F the can last of be any member of the family of section. functions of the antiderivatives of f, 2 This gave the area under the cur ve f (x) = x + 1 we between x = 0 and x = choose to use the ‘simplest’ one, 2. that is, one where the constant of 2 2 Y ou found (x + 1) dx ≈ 4.67. integration is C = 0. We can do this 0 because, for any C, b f ( x ) dx = [F ( x) + C ] a = [F(b) = F(b) + – C] – [F(a) + C] F(a) Chapter Using the Fundamental Theorem of Calculus we get: 2 2 1 2 (x 1) dx 3 x x 0 3 0 1 3 x 1 3 (2 ) 2 1 3 (0 + x is the ‘simplest’ antiderivative 3 1 ) 0 2 of 3 3 x + 1. Evaluate x + x at and x = 0, then nd the 3 Example Evaluate 4.67 the definite integral 1 without using 3 a GDC. 3 1 2 (u a – 1) du dt b 4x c (x – 1) dx t –2 2 1 Answers 1 1 Find ⎡ 1 (u a – 1) du = ⎣ ‘simplest’ antiderivative of u – 1. u ⎢ –2 the ⎤ 2 u ⎥ 2 ⎦ -2 1 2 Evaluate ⎛ 1 ⎞ 2 (1 = ) − 1 ⎜ ⎝ ⎛ 2 1 1 ⎞ 2 − ( −2 ) ⎟ ⎜ ⎠ ⎝ − ⎜ – u at u = 1 and u 2 = –2, then find the dif ference. ⎠ 9 – ⎟ 2 u 2 ( −2 ) ⎟ ⎞ 1 = ⎝ ⎛ (2 + 2) = – 2 ⎠ 3 a 1 3 dt b Recall that ln a – ln b = ln = [ln t ] 2 b t 2 3 = ln 3 – ln 2 = ln 2 3 3 2 4x c 3 (x – 1) dx = 4 (x 2 – x Rewrite ) dx 1 1 3 ⎡ 1 = 1 4 3 x 4 ⎥ 4 ⎣ ⎡⎛ = 4 ⎢ ⎣ 3 1 ⎝ ⎣ ✗ Evaluate ⎞ −9 4 Exercise ⎞ 3 (3 ) 3 ⎜ ⎝ 1 1 ) 4 4 ⎢ ⎦ 4 (3 ⎜ ⎡ ⎛ 81 = ⎤ x ⎢ ⎟ ⎠ ⎛ − ⎠ ⎛ − ⎟ 1 ⎝ ⎝ 1 4 ⎞⎤ 1 4 (1 3 ) − 4 ( 1 3 ⎞⎤ ) ⎟ ⎠ ⎥ ⎦ 136 = − ⎜ 1 ⎜ ⎟ 3 ⎠ ⎥ 3 ⎦ 9I the definite integrals 1 in questions 1–8. 1 2 2x 1 dx (u 2 0 – 2) du –1 8 1 2 3 3 2 x 1 dx 1 Integration ⎞ 3 4 ⎜ 2 ⎛ 0 ⎝ x = 2 difference. 14 ≈ x 3 3 x ⎟ ⎠ dx the integrand in order to integrate. 2 3 e 1 x 4e 5 dx dx 6 The force between x 0 e electric 9 1 2 (t 7 + 3)(t + 1) dt charges depends x on the 3 dx 8 amount of and distance the charge x 4 0 the between Exam-Style the charges. Questions How are denite 2 integrals It 9 is given that f (x) dx = used to 8 calculate the work 0 2 Write a down the value of done 3f (x) when charges dx. are separated? 0 2 2 Find b the value of (f (x) + x ) dx 0 k 1 10 Given dx = ln 6, find the value of k x 2 Now we linear look at function Example Evaluate definite ax + b or integrals the that involve substitution compositions with the method. the definite integral without using a GDC. 1 5 1 ⎛ a ⎜ ⎞ 2 x e 3 dx + 2 x ⎝ (2x b –3) dx ⎟ –1 ⎠ 1 1 3 2 3x c + 16 dx (2x d 3 + 1) (4x) dx 0 0 Answers 5 1 ⎛ 1 ⎞ 2 x ax + b + e a ⎜ that e ax+b dx = e + C. a x ⎝ Recall dx ⎟ 2 ⎠ 1 5 2x = –2 (e + x ) dx 1 5 ⎡ 1 1 ⎤ 2 x e = ⎢ ⎣ ⎛ ⎥ x 2 1 − 2 5 1 ⎜ ⎠ ⎝ e 1 ⎞ 2 (1 ) e ⎟ 1 − ⎟ 2 1 ⎠ 4 10 = ⎛ 1 − ⎜ ⎝ 1 1 ⎞ 2(5) e = ⎦ 2 − 2 e + 2 5 10 5e 2 − 5e + 8 or 10 { Continued on next Chapter page 1 n Recall 3 (2x b – 3) that (ax + dx b) = dx –1 1 ⎡ 1 ⎛ 4 (2 x 3) ⎜ ⎢ 2 ⎣ 1 ⎛ ⎞⎤ 1 = a 4 ⎝ ⎠⎦ ⎛ 1 4 8 1 625 8 8 = = ⎝ ⎞ ⎟ + C. ⎠ ⎞ ⎛ 1 ⎟ ⎜ ⎠ ⎝ 4 ⎞ ( 2( −1) − 3) ⎜ ⎝ n+1 ( ax + b ) n + 1 1 ( 2(1) − 3) = 1 ⎜ ⎟⎥ ⎟ 8 ⎠ –78 3 c 3x n dx + 16 Recall that (ax + b) dx = 3 0 1 = (3x + 16) 2 dx 1 ⎛ 1 n+1 a 3 ⎝ ⎞ + ( ax + b ) ⎜ 0 C ⎟ n + 1 ⎠ 3 ⎡ 1 ⎛ 2 ⎢ ⎜ ⎞⎤ 2 = 3 ⎢ ⎣ (3 x + 16 ) ⎟⎥ 3 ⎠⎥ ⎦ ⎝ 2 ⎛ = 0 3 3 2 (3(3) + 16) ⎜ 2 – (3(0) + 16) 9 ⎞ ⎟ ⎠ ⎝ 3 3 3 ⎛ 2 ⎞ ⎜ = 25 – 16 ⎟ 3 2 122 2 2 Recall 25 25 ) = 125 and = 3 ⎝ 9 ⎠ 9 2 3 16 16 ) = 64. 1 and 1 2 (2x d 3 + 1) (4x) dx 0 x = 1 du du 3 = 2 u dx Let u = 2x + dx Change u = 3 3 ⎡ 1 3 = u du = 4 4x and substitute. ⎣ the limits of integration and then you can ⎤ u ⎢ u = 1 evaluate the integral in ter ms of u. When ⎥ 4 ⎦ 1 2 x = 1 0, u = 2(0 ) + 1 = 1, and when x = 1, 2 4 = = dx x = 0 u 4 [(3) – (1) ] = = 2(1 ) + 1 = 3 20 4 Exercise ✗ Evaluate 9J the definite integrals in questions 1–8. What are some 4 1 1 x dt t + 1 e applications dx center 3 of 1 3 (–2x + 1) x dx mass How 2 of + 2 –1 (e (centroid)? can denite –x + e ) dx integrals be used to –1 –1 nd 2 2 centroid 6x dx 4 (x 3 + x) (2x 1 0 4 1 8t 6 2 x dt 2 2t 3t 3 the 2 Integration 4x e 2 0 3 dx + 1) dx cur ved area? of a Exam-Style Questions y 2 The 9 diagram Write a down shaded Find b shows par t an of the integral graph which of f (x) = represents –2x the (x – area 2) of the region. the area of the shaded region. x 0 y 1 10 The diagram The area shows par t of the graph of y = x Find .5 We to the the area sums He such the the of two are of ln 4 1 units. 0 k. two of of area under used Riemann Georg the x k a cur ve to sums Riemann. limits of sums. { Investigation: Consider the area Georg Area between Riemann (1826–66) between the two two curves cur ves y 2 f(x) 2 curves rectangles named existence is cur ves. mathematician the region concept areas area German proved value between of shaded between extend approximate after the exact Area now The of = x + 3x 22 and 20 g(x) = x – 2 from x = –1.5 to x = 3.5. 18 16 14 12 10 2 f(x) = x + 3x 8 6 g(x) = x – 2 4 2 x –4 –6 Continued on next Chapter page Copy 1 of and the complete ve the rectangles Inter val table shown to in give the the dimensions and area of each graph. Width Height Area Notice –1.5 ≤ x < –0.5 –0.5 ≤ x < 0.5 1 f(–1) – g(–1) = –2 – (–3) = 1 1(1) = 1 that, regardless whether f positive, 0.5 ≤ x < or zero, of the ≤ x < ≤ x g are the height rectangle given by is f(x), 2.5 the 2.5 and negative 1.5 always 1.5 of < top g(x), 3.5 cur ve, the minus bottom cur ve. Approximate 2 areas Write 3 of the down the area between the cur ves by nding the sum of the rectangles. a denite integral you think can be used to nd the exact area 2 between x = the the Compare the If y y and 1 a cur ves f(x) = x + 3x and g(x) = x – 2 from x = –1.5 to 3.5. Evaluate ➔ two ≤ integral on answer are your to GDC. your approximation continuous on a ≤ x ≤ b from and y 2 x ≤ b, question ≥ y 1 then the area between and y y 1 for 2. all x in 2 from x = a to x = y b 2 b is given by (y – y 1 ) dx 2 a y – 1 y 2 y 1 Height of each rectangle = ‘top cur ve’ – ‘bottom cur ve’ = y – y 1 Width Area of of each each rectangle rectangle = = ( y dx – y 1 Sum of the areas of an 2 dx x 0 ) dx 2 infinite number of rectangles from x = a b y 2 to x = b and exact area between the two curves = (y – 1 y ) dx 2 a Example 2 a Graph Write Solve the region down this an bounded expression problem by the that without cur ves gives using a the y = x area – of 2 and the y = region –x. and then find the area. GDC. x – 2 b Sketch Write Find the graph down the an area, of the region expression using a that bounded gives the by the area curves of the f (x) = 2e 2 and g(x) = x Integration 4x. region. GDC. { – Continued on next page Answers Find 2 a x – 2 = by 2 x + x the – 2 = + setting 2)(x – 1) = = –2, Points the two cur ves the for equations x. Substitute equal the and x-values into 0 either x of 0 solving (x intersection –x equation to get the y-coordinates. 1 of intersection: (–2, 2) and (1, –1) 2 y The graph of y = x – 2 is the graph 2 4 of y = x translated down 2 units. The 2 y = – x 2 3 graph 2 (0, 0) of y and = –x is a gradient line with –1. The y-intercept graphs (–2, 2) intersect 1 0 –3 at (–2, 2) and (1, –1). x –2 3 –1 (1, –1) y = –x –3 1 1 2 Area = ((–x) – (x 2 – 2)) dx = (–x – x + y 2) dx = –x is greater than or equal to 2 –2 –2 y = x – 2 for –2 ≤ x ≤ 1, so the ‘height 1 1 ⎡ = 1 3 − x ⎤ 2 − x by (–x) rectangle’ is represented ⎥ 3 ⎣ 2 1 ⎛ ⎦ 1 3 (1) − 2 2 ⎞ 2 − (1) + 2(1) ⎜ 3 ⎝ ⎛ = each + 2x ⎢ = of 2 1 1 3 2 ⎝ ⎞ ⎛ 8 ⎟ ⎜ ⎠ ⎝ + 2 − ⎜ 1 ⎛ − ⎜ ⎠ ⎝ ⎟ ( −2 ) 2 GDC to 2). + 2( −2 ) ⎠ 9 = ⎠ 2 y b – ⎞ 2 − (x ⎟ 3 ⎞ − 2 − 4 3 ( −2 ) − ⎟ 1 3 – 4 Use a and to points 3 find of help the sketch the x-coordinates intersection. Write graphs of the down at x least 2 f(x) = 4 significant digits since these 2e values will be used to compute the area. 1 0 –2 x 1 –1 2 –1 –2 2 g(x) –3 = x – 4x –4 x 2 2e 2 = x – 4x x f(x) x ≈ –0.5843, = 2e 2 is greater than or equal to 4.064 2 g(x) 4.064 Area = ((2e –0.5843 = x – 4x for –0.5843 ≤ x ≤ 4.064, x 2 2 ) – (x – 4x)) dx ≈ 14.7 so the ‘height represented of each rectangle’ is by x ( 2 GDC ) 2 – (x – help on CD: 2e demonstrations Plus and GDCs Casio are on 4x). Alternative for the TI-84 FX-9860GII the CD. Chapter Exercise In 9K questions Write Find 1–4, down the an area graph the expression using a region that bounded gives the by area the of given the cur ves. region. GDC. 1 1 2 1 y = – 2 x + 2 and y = x – 2 2 2 2 2 f (x) 3 y 4 g(x) = x and g(x) = x 3 = 2x – 4, y = x between x = –2 and x = 2 2 = x + 1 Exam-Style ✗ and h(x) = 3 + 2x – x Question 4 5 Consider the a Find the b i Find ii Hence function f (x) = 2 x – x . x-intercepts. f ′(x). find the coordinates of the minimum and maximum points. c i Use ii Sketch your answers to par ts a and b to sketch a graph of f 2 Write d questions cur ves. Find 6 y 7 f lnx f (x) = x 8 f (x) = e 9 y y and sketch an using and of x find a = 1 the graph – – that x on gives area of expression your = g(x) expression g down area = an and 6–9, Write the graph down between In a the that of the same the the region gives area axes. of the region region. bounded the area of by the the given region. GDC. 2 2 – 3x + 1 and g (x) = x x h (x) y = – x x + – x 6 2 Question the Sketch b i functions the Write graphs down between Find The 2 – 1 a c 3 1 and Consider ii = 2 Exam-Style 10 + 2 and = x –x f this line x of an and f (x) f = x and and g on expression g (x) the for = 2 same the area x axes. of the region g area. = k divides the area of the region from par t b in half. i ii Write down from par t Find the Integration an expression b value of k for half the area of the region Now we a ≤ look at cases where y and y 1 ≤ x b, but y is not greater are continuous or Use equal to y 1 a ≤ x ≤ b. In on 2 than for all x this case you must find all the nd points of determine determined which by the cur ve points is of above the other in the inter vals the the above in formed (x) down = of and which the cur ve other an expression 2 f help x-coordinates points determine cur ve Write to intersection intersection. is Example GDC intersection of and a in 2 10x + that gives 3 x – the area of the region and g(x) = x of – 2x. Find the by inter vals the points between 2 3x the intersection. area. Answer 2 10x + x 3 – Find 2 3x = x – of x = –2, 0, the points of intersection 2x f and g. 2 2 g(x) = x – 2x is greater than or 0 2 2 2 ((x – 2x) – (10x + x – 3x 3 equal to f(x) = 10x + x 3 – 3x )) dx for 2 –2 ≤ inter val x ≤ the 0, so on ‘height this of each GDC help on CD: Alternative 2 2 + ((10x + 3 x – 3x demonstrations 2 ) – (x – 2x)) dx rectangle’ is represented 2 (x 0 – 2x) – (10x + x = 24 f(x) = 10x + and Casio TI-84 FX-9860GII 3 – 2 the by Plus 2 for 3x ). GDCs are on the CD. 3 x – 3x is greater 2 than –2x or equal for 0 inter val ≤ x the rectangle’ to ≤ Exercise In 1–4, bounded 3 = x write by the down two 2 – x is so x on of 3x ) this each represented 3 – = by 2 – (x – 2x). 9L questions region + 2, ‘height 2 (10x g(x) 1 y 2x 2 f (x) = (x 3 f (x) = xe 4 g(x) an expression cur ves and then to find find the the area of the area. 2 and y = 2x – 3x 3 – 1) and g(x) = x – 1 2 x 3 and 4 = – x g(x) = x – x 2 + Exam-Style 10x 4 – 9 and h(x) = x 2 – 9x y Question 1 2 5 The cur ves shown in the figure are graphs of f (x) = x 6 , 4 2 g(x) a = – x and i Find ii Show h (x) the = 2x – coordinates that the line 4 4. Q of point passing 2 Q through points P and Q is 0 x 3 4 5 –2 1 2 tangent to f (x) = x at point Q –4 4 b i Find the coordinates ii Hence write region and down then of an find point P correct expression the for to 4 the significant area of the digits. shaded area. Chapter . Volume of revolution Solids of revolution manufacturing A solid of is revolution formed by rotating a plane First an axis of consider Imagine a used items in such figure as about are many pistons and crankshafts. revolution rectangle rotating the per pendicular rectangle 360° to about the x-axis. the x-axis. y y [ 0 0 Pistons x x The solid that cylindrical in is formed is called a disk. The disk is shape. y dx 2 V = πr = πy h cylinder 2 y dx [ 0 Crankshaft x Investigation – volume of revolution y Consider the triangle formed by the line 4 f(x) f (x) = 0.5x Copy and and the x-axis complete between the table x to = 0 give and the x = 6 = 0.5x 3 2 dimensions 1 and volume rectangles of each shown of in the the disks gure formed are when rotated the 360° x 1 2 3 4 5 6 7 8 9 –1 about the x-axis. The last row in the table below –2 is completed for you. –3 y Inter val Radius Height Volume height 4 0 ≤ x < 1 1 ≤ x < 2 2 ≤ x < 3 = dx 3 2 radius = y 1 3 ≤ x < 4 4 ≤ x < 5 x –2 4 8 –1 2 5 ≤ x < f(6) 6 = 3 6 – 5 = 1 π (3 )(1) ≈ 28.27 –2 –3 2 F ind the sum of the volumes of the six disks in y question 1. Is this sum greater or less than the exact volume 3 of the solid formed by rotating the triangle about the x-axis? 2 Write the down exact a denite volume of integral the solid you of think can revolution be used formed to nd when 1 the 0 x 3 triangle is rotated about the x-axis. Evaluate the integral on –1 –2 a GDC and compare it to your estimate in question 2. –3 When is a and the cone. triangle Use compare Integration it a is rotated geometric to the value about the formula of your to x-axis nd the the denite solid volume integral in formed of the cone question 3. 4 5 8 y ➔ If y = f (x) is continuous on a ≤ x ≤ b and the region bounded dx by y = f (x) and the x-axis between x = a and x = b is rotated y 360° about the x-axis then the volume of the solid formed = f(x) is y given by 0 2 V π (f = x b b 2 (x)) dx π y or a dx. a y Radius Height of of disk disk (height (width of of ‘representative ‘representative 2 Volume of Sum the disk πr = rectangle’) rectangle’) = y = d x 2 h= πy dx 0 of volumes of an innite number of disks from x = a to x = a b b x b 2 and exact volume of the πy solid dx. a Example Use a definite integral to find the volume of the solid formed when the region bounded 2 by f (x) using = a 9 and x geometric the x-axis is rotated 360° about the x-axis. Verify your answer formula. Answer Sketching y 4 a graph and ‘representative rectangle’ is helpful. Radius of disk is the height dx 2 2 y √9 = – 2 of x representative rectangle, 9 x . 1 Height of disk is the width of representative rectangle, x –4 –3 –2 0 –1 1 2 3 4 5 dx. b The limits Use a of integration are the x-intercepts, –3 and 3. 2 V π y = dx a 3 2 2 π = ( 9 ) x dx GDC to evaluate the integral. −3 ≈ To 113 verify: 4 4 3 V πr = 3 π(3 = When ) about = the region is rotated y x-axis, 36 π a ≈ the 3 3 sphere is 2 for med. 113 4 3 Volume of sphere πr = 3 x 0 –4 1 4 –2 Exercise Use the a definite region x-axis. 1 f 9M (x) Verify = integral bounded 4 your and by to find the answers the x-axis the given using volume cur ves is of geometric between x = 0 the solid rotated formed 360° about when the formulae. and x = 5 Chapter f 2 (x) = 6 – 2x and the x-axis between x = 0 and x = 3 Ibn al-Haytham (965–1040), mathematician who lived a mainly in 2 f 3 (x) 4 = x and the x-axis Egypt, the is credited integral of a with calculating function in order to 2 f 4 (x) 16 = x and the x-axis between x = 0 and x = 4 nd the f 5 (x) = x and the x-axis between x = 2 and x = the 3-D volume shape Use a a paraboloid created by – rotating a 4 parabola Example of about its axis of symmetr y. definite integral to find the volume of the solid formed when the region under the cur ve 2 y = x between x = 0 and x = 2 is rotated about the x-axis. Give your answer in terms of π. Answer y b 5 2 V πy = dx 4 a 2 3 2 π(x = 2 ) 2 dx y 2 = x 0 1 2 4 πx = dx dx –4 –3 –2 0 –1 1 x 2 4 3 0 2 ⎡ 1 = 5 Sketching ⎤ π ⎢ ⎣ ⎥ 5 ⎦ graph and ‘representative rectangle’ is helpful. 0 Radius ⎛ 1 = a x π 1 5 (2 (0 rectangle, ⎟ 5 disk is the height of representative 2 ) ⎜ ⎝ of ⎞ 5 ) 5 x . ⎠ Height of disk is the width of representative 32 rectangle, dx. = 5 The Exercise limits of integration are 0 and 2. 9N ✗ In questions solid 1–4, formed about the by use a definite rotating the integral region to find bounded the by volume the given of the cur ves x-axis. 3 1 f (x) 2 y 3 f = x and the x-axis between x = 1 and x = 2 2 = x + 1 and the x-axis between x = 0 and x = 1 2 (x) = 3x – x and the x-axis 1 4 y = and the x-axis between x = 1 and x = 4 y Exam-Style Question 1 x 5 The diagram shows par t of the graph of y = 4 . e The shaded 1 (4 1 x region to a x = Write the b between ln 4 is down solid This graph a 360° definite of y = about and e the integral is equal to kπ. = x ) e the x-axis that Find from x = 0 x-axis. represents the formed. volume Integration the rotated y 4 the value of k. volume of 0 ln 4 x Exam-Style Question y 1 The 6 shaded region in the diagram is bounded by y = , x x = 1, x = a and the x-axis. The shaded region is rotated 360° 1 about the x-axis. y = √x Write a of . the The b down solid a definite integral that represents the volume formed. volume of Definite the solid formed integrals 3π. is with Find linear the value of 0 a motion 1 a Extension material on Worksheet 9 volumes of and other Another application function over solids the of - More CD: revolution problems of definite integrals is finding the change in a Recall time. that if displacement then Suppose x displacement function for a par ticle moving along velocity = = s(t), v(t) = a s′(t) and acceleration 2 horizontal line is given by s(t) = t – 4t + 3 for t ≥ 0, where t is = measured in seconds and s is measured in metres. The a(t) = v ′(t) = s″(t). initial 2 displacement time 0 of seconds the the par ticle, par ticle s(0) is 3 = 0 – metres 4(0) to + the 3 = right 3, tells of the us that at origin. The 2 2 – metre to s(2) = 4(2) + 3 = –1 tells us that at time 2 seconds the par ticle displacement is function 1 the left of the tells us the origin. distance and direction 2 a v(t) Consider dt. Since the antiderivative of velocity is par ticle is from an displacement origin 0 at any time t 2 2 we have v(t) dt [ s ( t )] = = 0 s(2) – s(0) = –4. 0 Note t = that t = = 2t – 4, 0 and s(t) –1 0 1 2 3 4 5 6 7 4 v(t) metres = 2. gives from us the change in displacement from time 0 to 2 us that at 2 seconds negative the par ticle is 4 metres to the at left it was at 0 t = changes to 2, so par ticle changes of direction where when seconds. the tells 0 Velocity positive This = 8 t It v(t) 2 when t = 2. seconds. t ➔ v(t) dt = s(t ) – s(t 2 ) is the change in displacement from t 1 to t 1 2 t 5 Now consider v(t) dt = s(5 ) – s(0 ) = 8 – 3 = 5. This tells us that 0 at 0 5 seconds the par ticle is 5 metres to the right of where it was at seconds. t t = = 5 0 s(t) –1 0 1 2 3 4 5 5 6 7 8 metres Chapter Note that distance the change traveled traveled is traveled to the total the of right 9 in displacement between 4 or 0 and metres 13 5 of traveled metres 5 metres seconds. as to The the shown is not total left the total distance plus 9 metres below . metres t t = = 5 0 s(t) –1 0 1 4 2 3 4 5 6 7 8 metres y We will consider this in terms of the area under the cur ve of 6 v (t) = 2t – v(t ) =2t – 4 4. 5 4 Let the area of and the area of the triangle below the x-axis be A the 1 3 5 A triangle above the x-axis be A . v (t)dt is the negative of 2 2 2 plus A 0 A 1 1 2 0 x 1 5 2 3 4 5 6 –1 1 1 A 1 |v (t)|dt = –A + A 1 = – (2)(4) + (3)(6) = –4 + 9 = 5. –2 2 2 2 0 –3 –4 This To gives find we us the need the total the displacement distance sum of the from traveled areas A time from and to time A 1 0 . 5 0 We seconds. to 5 can |v(t)| seconds find this by means the absolute value modulus of or 2 5 evaluating v(t). |v (t)|dt 0 y 5 1 v (t) dt = A + A 1 1 = (2)(4) 6 + (3)(6) = 4 + 9 = v(t ) 13 =|2t – 4| 2 2 0 2 4 This gives us a total of 13 metres traveled from time 0 to 5 seconds. 3 A 2 2 A 1 ➔ If v the is the total velocity function distance for traveled a particle from t to 1 t moving is given along a line, 1 by: 0 2 distance = x 1 t 2 3 4 5 6 |v (t)| dt. t Example The displacement function for a par ticle moving along a horizontal line is given by 2 s (t) = 8 + 2t – a Find the b Find when c Draw d Write total and a t for velocity the distance use ≥ of 0, where the particle motion definite then t diagram traveled the is par ticle is integrals t at moving for to on motion measured the find the time right in seconds and s is measured in t. and when it is moving left. par ticle. the par ticle’s inter val diagram to 0 ≤ t verify change ≤ 4. the Use in a displacement GDC to and evaluate the the Integration integrals results. { metres. Continued on next page Answers a v(t) = b 2 2t – 2 – = 2t v(t) = Find t c = s′(t) 0 when velocity equals zero. 1 s Moves right Moves left s(0) = 8 for 0 when and < t s(1) t > = < 1 The 1 v(t) 9 par ticle < v(t ) t t = = moves right when v(t) > 0 and left when 0. + 1 0 t = 0 1 s(t) 0 1 2 3 4 5 6 7 8 9 Find d Change in dispacement at t = 0 and t = 1. displacement t 4 Change = (2 – 2t)dt = in displacement = v(t)dt – 8 m t 0 4 Total distance = t |2 – 2t|dt Total distance = |v(t)|dt t 0 = 9 t = 10 m metres t 4 t = = 1 0 s(t) 0 1 2 3 4 8 5 6 7 8 metres 1 9 metre Show s(4) par ticle at 0 of 8 0 GDC to traveled metres metres help on to and CD: GDCs Casio are on the from demonstrations Example the metres par ticle 9 10 Plus on diagram. the left At of 4 seconds where it the was seconds. The and is = 1 left time metre for 0 a to to the total 4 right distance seconds. Alternative for the TI-84 FX-9860GII the CD. –1 The velocity function v, in m s , of a par ticle moving (8, 4) 4 along a line in traveled is shown in displacement on the inter val the figure. and 0 ≤ t the ≤ Find total 16. the par ticle’s distance )dnoces change 3 2 1 rep t (seconds) 0 sertem( 2 4 –1 –2 v (14, –2) (15, –2) –3 –4 { Continued on next Chapter page Answer 4 Let A , A and A 2 triangles be the areas of the two 3 and Change the in )dnoces 1 trapezium. displacement rep 16 sertem( = v(t)dt 0 – A + A 1 – )t(v = A 2 3 3 2 A 2 1 t (seconds) 0 2 4 –1 A A 3 1 –2 –3 1 1 = – (4)(4) 1 + (8)(4) – 2 2 Total (4 + 1)(2) = 3 m –4 2 distance )dnoces 16 = |v(t)|dt A + A 1 + 3 (4)(4) = (8)(4) 29 of (4 + 1 A A 1 A 2 3 t (seconds) 0 2 4 6 8 10 12 14 16 18 1)(2) 2 m 9O questions inter val, + 2 Exercise Each 1 + 2 2 )t(v 1 1 = A 2 3 sertem( = rep 0 4 where the t is 1–3 gives a measured a Find b Draw a velocity c Write definite motion displacement of displacement in the par ticle diagram integrals and the seconds for to the find total function and at s is and time measured in metres. time t. par ticle. the par ticle’s distance change traveled on the in given time inter val. Use a GDC diagram to to evaluate verify the the integrals and then use the motion results. 2 1 s(t) = 2 s(t) = t – 6t + 8; 0 ≤ t ≤ 4 1 3 t 2 – 3t + 8t; 0 ≤ t ≤ 6 3 3 3 s(t) = 4 The (t – 2) ; 0 ≤ t ≤ 4 (5, 6) –1 line is function shown displacement and the the inter vals. ≤ t ≤ 12 b 0 ≤ t ≤ 5 c 0 ≤ t ≤ 12 figure. total , of Find a the distance par ticle moving par ticle’s traveled for along change each in of the 6 5 4 3 2 1 t (seconds) 0 v 2 m s sertem( a in rep following in v, )dnoces a velocity 2 4 –1 –2 (9, –2) Integration (11, –2) Exam-Style Questions –1 The 5 velocity , v, in m s of a par ticle moving in a straight 2 line is given a Find b The c the by an Find the = t – acceleration initial Find v (t) 9, where of the displacement expression distance for of s, is the par ticle the the traveled t time at t par ticle = is times seconds. 1. 12 displacement, between in metres. in 2 terms seconds of t and (4, 4) 8 4 seconds. line is function, shown Find b Write the the the m s of a par ticle moving along figure. acceleration down in time when t = sertem( a in v, 3. inter val(s) on which the par ticle is )t(v traveling to the Find total 3 2 rep a ✗ velocity )dnoces –1 The 6 1 t (seconds) 0 4 –1 –2 (13, –2) (15, –2) –3 right. –4 c the distance traveled for 0 ≤ t ≤ 16. The Definite integrals can be used in situations other than linear of We can use definite integrals to find the cumulative effect integral of a rate motion. of change is the total any change from t to 1 var ying rate of t : 2 change. t 2 F′ (t)dt = F(t ) – F(t 2 Example A culture bacteria. of bacteria The ). 1 t rate at is star ted which with the an number inital of population bacteria of 100 changes over a one- 0.273 t month r is period measured Find the can in be modeled bacteria population of per by the function r(t) = e , where day . bacteria 20 days after the culture was star ted. Answer 0.273t r(t) is = the R(t), e is a rate derivative that bacteria gives at of a the time t. of change. function, number It say of Therefore 20 r(t)dt = R(20) – R(0) Notice 0 is the change bacteria Since from the in the day initial 0 number to day of show 20. population was that that results 100 in the the a units integral number of bacteria. 20 bacteria, the population after 20 0.273 t 20 0.273t days is 100 + e dt or dt bacteria ( days ) (per 0 about e day ≈ 857 bacteria ) 0 957 bacteria. You could using the method get the same following (see { next result longer page). Continued on next page Chapter 0.273t R(t) = e dt Find the R′(t) = function r(t). R(t), such that Recall that 1 1 0.273t = e 0 dt + C ax + b e 273 ax + b dx = e + C. a 1000 0.273t = e + C 273 000 0.273(0) 100 = e + C Use 273 R(0) 1000 C = 100 the = initial 100 condition to find that C. Notice how much – 273 more convenient it 26300 to = obtain the same 273 result 1000 using 20 26300 0.273t R(t) = e + 0.273t 273 100 273 + e 0 26300 000 0.273(20) R(20) = e + ≈ Exercise Write an answer 1 The 1, ≈ R(20). 9P expression these. rate 2000 Find 957 273 273 Use of to a involving GDC to 1, definite evaluate consumption Januar y a of 2010 oil (in in integral the a that can be used to expression. cer tain billions of countr y barrels from per Januar y year) is t modeled years Find 2 The by since the the function Januar y total number 1, C ′(t) 18.4e 20 , where t is the number spectators of oil who over enter the a 10-year stadium period. per hour for 2 football 0 ≤ t 1.5 There at 0 t = From are hours. many There is is modeled hours. hour. How 3 ≤ game The no cubic midnight to the function game spectators 36.5 by spectators The of a.m. in snow is the at the snow function r(t) r(t) in begins are cm 8 time t = stadium on a = 1375t measured stadium 1.5 driveway accumulates in modeled by the function s(t) = the the at for per gates game the open begins? driveway 3 + t midnight. 4 rate – hours. on 0.01t a 3 people when when (– a of 2000. consumption of = 0.13t at 2 – 0.38t – 0.3t + 0.9) , 5te 3 where How 4 is measured many Water The t cubic begins rate at in cm leaking which it hours of snow from is and a are tank leaking, s in on . cm the driveway holding measured 4000 in modeled by the function r (t) = –133 8 gallons gallons per a.m.? of . 1 How much Integration water is in the tank at the end 60 of 20 water. minute, t be at minutes? can 957. dt is Review exercise ✗ 1 Find the indefinite integral. 3 3 4 3 (4x a – 8x + 6) dx x b dx dx c 4 x 4 5x 3x 4x dx d 2 e e dx 3 f x i (3x l 2x 4 (x + 1) dx 2 6x ln x 1 2 dx g 2x dx h + 1)(6x) dx x + 3 x 2 2 x 2e dx j 3 k 2x dx 5 e dx x e 2 Find the definite integral. 16 2 2 e 4 4 2 (3x a – 6) dx dt b dx c t x 4 0 1 1 2 1 2 3 x 3 6x e d 1 3 dx (3x e – 1) dx dx f 0 Exam-Style 2x 0 –1 + 1 Questions 2 3 The diagram shows par t of the graph of f (x) = x – 1. Regions A 2 y y and B are = x – 1 shaded. 3 a Write down b Calculate c Write an expression for the area of region B 2 the area of region B 1 B down an expression for the total area of shaded regions 0 A and B. Region d (Y ou B is need rotated not evaluate about the the x-axis. Write down x 1 –2 expression.) A 2 an –2 expression evaluate 4 A cur ve the with gradient for the volume of the solid formed. (Y ou need not expression.) equation function is y = f ' (x) f = (x) 3x passes – 2. through Find the the point equation of (2, the 6). Its cur ve. 5 5 Given that f 5 (x) dx = 20, 1 deduce the value of 5 1 f a (x) dx; [f b (x) + 2] dx 4 1 1 −1 6 A par ticle moves along a straight line so that its velocity , v m s 2t at time t seconds displacement, for s in terms s, of is of given the by v (t) par ticle = is 4e 8 + 2. metres. When Find t an = 0, the expression t k 1 7 Given dx 2x = ln 5, find the value of k 1 1 Chapter Review exercise Exam-Style 1 Find the Questions volume of the solid formed the x-axis when the region bounded 2 by f (x) = 4 – x and is rotated 360° about the x-axis. –1 2 A par ticle moves along a horizontal line with velocity v m s 2 given by v (t) = 2t – 11t +12 where t ≥ 0. 2 a b c Write down terms of an expression par ticle is of and value Find to the the time the acceleration, a m s , in t. The a for total 5 moving of to the left for a < t < b. Find the value b distance the par ticle travels from time 2 seconds seconds. 3 3 a Find the equation of the tangent line to f (x) = x – 2 at x = –1. 3 b The tangent Find the c Graph d Write and f and an the line intersects coordinates the tangent 9 line f (x) this tangent expression CHAPTER of for = x – 2 at a second point. point. line. the and area then enclosed find the by the graphs of f area. SUMMARY Antiderivatives and the indefini te integral 1 ● n Power rule: x n 1 dx x C , n 1 n 1 ● Constant rule: ● Constant multiple ● Sum or More k dierence on dx = kx rule: rule: indefinite + kf ( f C (x) dx (x) ± = k f g(x)) dx (x) dx = f (x) dx ± g (x) dx integrals 1 ● dx ln x C , x 0 x x ● e x dx e 1 n ● ( ax b) dx 1 n 1 ( ax b) C a n 1 1 ax b ● e ax b dx e C a 1 ● 1 dx ax b b ln( ax a b) C , x a Continued Integration on next page Area and definite integrals b y ● When f is a non-negative function for a ≤ x ≤ b, f (x)dx y a gives the area under the cur ve from x = a to x = = f(x) b. b ∫ f(x)dx a ● Some properties of defini te b integrals b 0 kf (x) dx = k f a x b (x) dx a a b b b (f (x) ± g (x)) dx = f a (x)dx ± g (x) dx a a a f (x) dx = 0 f (x) dx = – a b a f a b c f (x) dx f is is an (x) dx + f a Fundamental f b = a If (x) dx b a (x) dx c Theorem continuous antiderivative function of f on a of on ≤ Calculus the x ≤ inter val a b, ≤ x ≤ b and F then b b f ( x ) dx = ∫ [F ( x )] = F (b ) − F (a ) a a Area ● If between y and y 1 a ≤ are two curves continuous on a ≤ x ≤ b and y 2 x ≤ b, ≥ y 1 then the area between y and y 1 for all x in 2 from x = a to x = b 2 b is given by (y – y 1 ) dx 2 a Volume ● If y by = y f = of (x) f (x) revolution is continuous and the on x-axis a ≤ x ≤ between b x and = a the and region x = b is bounded rotated y dx 360° y about the x-axis then b (x)) of the solid formed is = f(x) given y 2 πy or a dx 0 x a Definite and volume b 2 π ( f by the integrals other wi th linear motion problems t ● v(t)dt = s(t ) – s(t 2 ) is the change in displacement from t 1 to 1 t 2 t ● If v is the velocity function for a par ticle moving along a line, t the total distance traveled from t 1 to t is given by: distance = |v(t)|dt 2 t Chapter Theory of knowledge Know The your method The ancient was formalized. one, the Greeks ancient circumscribed Let be a the To of used find Greeks polygons areas of limits! exhaustion concepts an of estimate for constr ucted with the calculus the regular increasing regular long area of a with n of calculus circle inscribed numbers polygons before of radius and sides. sides inscribed in a n circle of radius one and be A the areas of the circumscribed n polygons. The ancient Greeks found that both and lim A lim a n n n→∞ were equal What Can π. to conclusion you n→∞ think of were they other able to draw applications of from limits these in real Although Newton vs. development culmination of of calculus centuries mathematicians all over of was work the tr uly world. mathematicians and a resolved, today generally believed Gottfried Isaac Wilhelm are recognized for the of calculus. One and develop conflicts in Leibniz over one of Moder n-day of the centur y , calculus first and is due them was to calculus the emerged effor ts in the of invented whether such as Augustin- the Cauchy (French), Ber nhard or (German), Karl any Weierstrass plagiarism one most histor y Riemann discovered of actual mathematical which independently Leibniz Louis argument that calculus mathematicians famous is Newton 19th development it The another. (German) debate fully by did (English) the never Newton 17th-centur y life? Leibniz was The facts? (German), IS AA C and involved. others. What are some possible consequences N when people seek personal acclaim for their Did the work of Suppose that Newton and Leibniz calculus independently of Would this offer suppor t need to the to calculus was discovered or solve cer tain that it problems or idea purely that from one real-world another. arise did the develop T work? mathematicians EW these from V S intellectual was curiosity? invented? GO TT FR I LE Theory of knowledge: Know your limits! ED IB W ILH N I Gabriel’s Consider the horn solid formed when the region bounded by 1 f (x) , = x = 1 and x = a, a > 1 is rotated about the x-axis. x If a → The ∞, the volume solid of the is known as Gabriel’s horn . solid y of revolution about the 3 x-axis is given by 2 b π∫ y²dx. It can be a 1 shown that the surface x 1 area of the solid is b by 2 3 4 a given -1 2π∫ 1 + (y')²dx a -2 Use a GDC to find, -3 to four places, above table. decimal the for volume the Then surface given make area and surface values a a. conjecture approach as = a 1 a a Volume of π∫ area of Write about the solid them what approaches in a the described copy volume dx and Surface area = 2π∫ 1 1 1 a ² the infinity . x 1 of [ 1 + 4 ] dx x x 10 100 1000 10 000 100 000 1 000 000 a → ∞ Volume Based take on to How the fill up much → results Surface in your Gabriel’s paint table, how area much → paint would it hor n? would it take to cover its surface? N Paradoxes A result that example of a dees logic paradox. is called Research a paradox. some other Gabriel’ s horn examples is one of paradoxes. LM Chapter Bivariate CHAPTER Linear 5.4 analysis OBJECTIVES: correlation coefcient r; of bivariate scatter data; diagrams, Pearson’ s lines of best product–moment t; mathematical correlation and contextual interpretation. The 5.4 equation of the regression line of y on x; use of the equation for prediction purposes. Before Y ou 1 you should Calculate start know simple how positive to: Skills exponents 1 Evaluate: 4 e.g. Evaluate 3 5 . a 2 b 3 c 7 4 3 check 3 = 3 × 3 × 3 × 3 = 81 3 3 2 ⎞ ⎛ e.g. Evaluate . ⎜ 7 ⎟ 5 ⎝ 1 ⎞ ⎛ ⎠ d ⎜ ⎛ ⎝ 2 2 × 2 × 2 5 × 5 × 5 4 = ⎟ 5 ⎠ 3 2 ⎞ ⎜ ⎟ 2 ⎝ 3 = 3 ⎠ 5 3 ⎛ e ⎜ ⎞ ⎟ 4 ⎝ ⎠ 8 = 3 f 0.001 125 2 Conver t numbers to exponential form 2 State the value n e.g. Find 2 2 n given 2 = 8. equations: n a × × 2 = 2 = 16 = 243 = 343 = 625 8 n b 3 3 2 = n 8 c 7 d 5 n n = 3 n e (–4) = –64 n ⎛ f ⎝ Bivariate analysis 1 ⎞ ⎜ ⎟ 2 ⎠ 1 = 8 of n in the following In 1956, an convincing cancer. He Australian case of souther n was was of skin In Chapter 5 population : A sample Suppose height The the x is This the cancer a that and the rate Oliver well of Lancaster, exposure of skin correlated nor ther n result dealt with por tion are weight bivariate the was consists we sampling that between with states before careful data in latitude, in and the collection the and Australia higher hole made sunlight cancer had the to hence rates and among with than ozone first skin the layer! His comparison rates. we it statistician, link strongly sunlight: ones. discover y a obser ved Caucasians amount for units data of of univariate all of the of are adult adult contains We measurements defined of a interest. population. interested y the analysis. in studying males. males all the of Sampling uni t Variable(s) Population adult males height univariate adult males weight univariate adult males height, bivariate and the pairs (x, y) weight of height ➔ and Bivariate pairs of weight of analysis variables is the males in concer ned (x, y) in a our with data sample. the relationships between set. Chapter In this data chapter using using a we will graphs, scale to describe Investigation The bell and soon its tower show was The the beyond of began name. the – Pisa in associations to So of in a the built side – in as an two sets equation of and relationship. of Pisa 1178 hence below millimetre 1975 metres of tower was one between relationship strength cathedral tenths 2.9642 a leaning leaning metres. leaning for measurements lean 2.9 look representing the from tower the ver tical. Y ear 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 Lean 642 644 656 667 673 688 696 698 713 717 725 742 757 Does If it so, look how like fast the is the Is there evidence Is there an Can you . lean lean that the Scatter the tower increasing the approximate predict of lean in increasing with changes formula lean is the for with time? time? signicantly calculating the with time? lean? future? diagrams Correlation One way to view data is by showing it on way ➔ Scatter investigate that (also diagrams both the possible relate to the called scatter relationship same plots) are between used two to diagrams horizontal a ver y and specific are similar ver tical axes pur pose. A to to associated to or affects variables The purpose The To line plot scatter graphs data in that points. diagram they use However, shows how allow they much have us from a the graph. the a dots to prediction variable one is doing to make about based we know a one on about another. relationship draw of ‘event’. between two variables is called scatter data The can diagram table as patter n give us dots plot the y) values of y on formed (x, variable. their correlation For ➔ are. variables another ➔ how related two what variable a measure correlations Scatter is a scatter diagram the Pisa think leaning that increases by time. some tower example, the we lean with Time is the independent indication of the correlation. Dependent variable. The depends on lean variable The be independent on the variable horizontal axis should with variable on the is 0 ver tical axis. Bivariate analysis time, the so dependent the Independent variable the the amount of lean dependent x variable. ➔ A general upward trend in the patter n of dots shows posi tive correlation. y The value of the dependent variable increases as the value of the 7 6 independent variable increases. 5 4 3 2 1 0 ➔ A general negative The downward in the patter n of dots 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 shows correlation. dependent variable trend x 1 variable decreases as the y independent 7 increases. 6 5 4 3 2 1 0 ➔ Scattered close to points with no trend may indicate x correlation zero y 7 6 5 4 3 Scatter Here diagrams are allow differing us to amounts assess of the positive strength of a correlation. 2 1 correlation: 0 y y y 10 10 10 9 9 9 8 8 8 7 7 7 6 6 6 5 5 5 4 4 4 3 3 3 2 2 2 1 1 1 0 x 1 Strong y 2 3 4 5 positive increases as 6 7 8 9 10 correlation: x x 0 x 1 2 3 Moderate 4 5 6 positive 7 8 9 10 correlation 0 x 1 Weak 2 3 4 positive 5 6 7 8 9 10 correlation increases Chapter Here are differing amounts of negative y correlation: y y 10 10 10 9 9 9 8 8 8 7 7 7 6 6 6 5 5 5 4 4 4 3 3 3 2 2 2 1 1 1 0 x 1 2 Strong 3 4 5 6 negative 7 8 9 0 x 10 correlation: 1 y decreases 2 3 Moderate 4 5 6 negative 7 8 9 0 10 x 1 x Not 3 4 5 6 7 8 9 10 correlation Weak as 2 negative correlation increases all relationships are linear. y 10 9 8 The points on this graph are 7 6 approximately linear. 5 4 3 2 1 0 x 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 y 10 9 8 7 The points on this graph would 6 be represented by a cur ve. 5 4 There is a non-linear relationship 3 between the 2 variables. 1 0 x Causation ➔ A correlation that Here is one an students’ words, has. to causes the example: the vocabular y the Now do between larger it with is the easy each shoe have other, data sets does not necessarily mean other. shoe to two see a sizes strong, size, that but of the positive larger shoe they grade are size students correlation. the and highly school In vocabular y vocabular y correlated. and other the student have The the nothing reason is Y ou may ‘causation there is a confounding factor , age. The older grade for school exploration. students will have Bivariate analysis larger shoe sizes and often a larger vocabulary . to use versus correlation’ stimulus that wish as an the Example a Represent this data on a scatter diagram. x 1 2 3 4 4 6 6 6 7 8 y 1 3 3 5 6 7 5 6 8 9 b Is c Describe the relationship the type linear and or non-linear? strength of the relationship. Answers a y 10 9 8 7 6 5 4 3 2 1 0 x 2 b This is 4 a 6 linear 8 relationship. Compare the There c is a strong, the examples scatter diagram with earlier. posi tive correlation. Exercise 1 0A Describe a correlation shown y 0 d the b e x each of these scatter diagrams. y 0 x y 0 by c x y 0 x y 0 x Chapter 2 For the following data i is the correlation ii is the relationship iii is the association a sets: positive, linear strong, negative or or is moderate, weak b y 6 5 5 4 4 3 3 2 2 1 1 0 0 x 1 2 3 4 5 6 7 8 9 10 y d 10 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 y 5 4 4 3 3 2 2 1 1 0 x 1 2 3 4 5 6 7 8 9 0 10 f y 10 9 9 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 x 1 and 2 3 4 5 complete 6 7 dependent then as variable independent correlation dependent Bivariate analysis then 9 these independent correlation 8 as variable x y 10 0 5 6 5 the 4 7 6 If 3 8 7 b 2 9 8 the x 1 10 9 If y 7 6 a zero? 8 7 Copy or 9 8 3 association 10 9 e no non-linear 10 c there 0 10 x sentences. and the dependent variables independent variable show a positive increases the ………………… and the dependent variables independent variable ………………… show a negative increases the This 4 table shows Year cm in Tennessee from 2000 to 2003 2004 2005 2006 2007 2008 42 51 39 44 31 33 30 28 21 this b Describe c In data the general, table on a scatter diagram. correlation. what shows Friend a has happened group of to friends the rainfall with their since the year mathematics Ted Tom T od May Ray Kay Jay Mathematics 85 75 66 80 70 95 90 60 Science 75 65 40 72 55 88 80 40 1 Draw a scatter 2 Describe the diagram correlation Investigation Construct a – scatter tower to of represent in terms leaning diagram Pisa for of this the investigation data at of direction Pisa from the science and form. (continued) the star t of Extrapolation this scores. data. strength, tower 2000? and Tim leaning 2008. 2002 Show a in 2001 a This rainfall 2000 Rainfall 5 the means estimating chapter . a b Describe c What the value a point that is larger than correlation. (or is at happening to the lean as the smaller than) the data you have. years Extrapolating here means assuming increase? that d Research the latest developments on the effor ts to save Comment . The on the the line leaning dangers of tower of best of the trend of the lean will remain the same. Pisa. extrapolation. fit y ➔ A line find to of the best or fit direction show the trend of trend. an This line is drawn on a association between line fit of best can scatter two then diagram variables be used to and to (x, y) make ➔ To predictions. draw will a line balance number of of the points reference point: the point best fit number below one by of eye the point draw points line. for the a line above An that the line with improvement line to pass is the to through. 0 have This a is The mean and is calculated by finding the mean of x mean written x-values and the mean of the point is the as ( x y ) y-values. Chapter Example Is there fast a relationship between the grams of fat and the total calories in food? Meal T otal fat Hamburger (g) T otal calories 9 260 Cheeseburger 13 320 Quar ter Pounder 21 420 Quar ter Pounder 30 530 31 560 Big with Cheese Burger T oasted Sandwich 31 550 Chicken Wings 34 590 Chicken 25 500 28 560 20 440 5 300 Crispy F ish F illet Grilled Chicken Grilled Chicken Light a Find the mean number of grams b Find the mean number of calories. c Constr uct d Plot of the best a scatter mean diagram point on your for of fat. this scatter data. diagram and use it to draw a line fit. Answers 247 a Mean grams of fat Mean = grams of fat 11 Total = grams of fat Hence = 22.45 Number of meals (x, y ) = (22.45, 457.27) 5030 b Mean no. of calories = Mean no. of calories 11 Total = 457.27 no. of Number c and calories = of meals d A ‘line of best t’ Calories is The line of best fit does not also called a have 600 regression to pass through (0, 0). It must through Mean point 400 the mean point and The British and statistician have the same number of data Francis points either side of Galton coined regression centur y. 100 0 10 20 Grams Bivariate analysis 30 of fat 40 (1822– it. 1911) 200 scientist ( x, y ) roughly 300 line pass 500 in the the term 19th Exercise 1 The 0B table width of a Length Width 118 125 136 145 25 30 38 50 36 42 52 48 58 62 mean a scatter (cm) table and draw a line of best fit through gives the heights and weights of ten sixteen- Abe Bill Chavo Dee Eddie Fah Grace Hanna Ivy Justin 182 173 162 178 190 161 180 172 167 185 73 68 60 66 75 50 80 60 56 72 (kg) b Constr uct i the a mean table mean in diagram shows the the 0 a line of scatter in hours best spent fit through studying and mathematics. 5 6 7 8 1 3 7 9 9 8 10 14 point. a grades of 4 mean mean draw 3 the Constr uct weight. 2 1 b and mean 1 grade Find the number students’ in a ii point. studying Increase height scatter below increase your diagram students. Find: Hours point. point. following a the and mm. 105 mean Weight The in length 95 Name 3 measured the 80 Constr uct your leaf between 78 b Height relationship 50 the year-old tree the 35 Find The shows mango a your 2 below What diagram and draw a line of best fit through the wish to the What can Y ou in correlation. nancial d of explore extrapolation Describe c risks extrapolation? may point. are you say about the effect of the number of or climate hours models. spent The equation mean of mathematics the line and of the best increase fit in grade? through the point Raw data with rough diagram ➔ studying rarely fit appears The line, a straight predictions. to equation can be ‘fit’ of used line exactly . Typically , a the for straight line of you line, best prediction Usually , have the fit, a set line also of you of must data best called be satisfied whose scatter fit. the regression pur poses. Chapter Example Miss and Lincy’s final 10 exam students’ are scores, shown out of 100, for their classwork below . Student Ed Craig Uma Phil Jenny James Ron Bill Caroline Steve Classwork 95 66 88 75 90 82 50 45 80 84 F inal 95 59 85 77 92 70 40 50 Abs 80 Caroline was absent for the final. a Find the mean classwork b Find the mean final c Constr uct d Find e Use the the a scatter equation equation exam of the the not include her grades in finding the mean point. score. diagram of Do score. and draw regression regression a line of best fit through your mean point. line. line to estimate Caroline’s score for the final exam. Answers Classwork a Mean classwork score total = Number of students 675 Mean classwork score = = 75 9 Final exam b Mean final exam total score = Number of students 648 Mean final exam score = = 72 9 c 100 erocs 80 Mean point maxe 60 lani F 40 20 0 20 40 60 Classwork 80 100 score y y 2 d Using the mean point and Uma’s Use m where x x 2 results, we have (x , y 1 ) = 1 , y 1 , y 2 ) = ) is the mean point 1 (88, 85) 2 and (x , y 2 m 1 (75, 72) (x (x 1 = 85 72 88 75 = = ) is any point on 2 the line. Use y 1 y = m(x 1 for the equation of The equation of the line x ) 1 the line. is: Using y – 72 = 1(x – best y = x – y = 80 t – 3 Caroline’s = 77 exam Caroline’s classwork score is estimated to be 77. score was 80. Let x = 80. data the of predict value range given than Bivariate analysis of data is within the called interpolation. generally line to 3 a e the 75) more It is reliable extrapolation. Exercise 0C EXAM-STYLE 1 QUESTIONS T omato plants scientist wishes the disease. percentage Percentage Draw the Find c Use 2 how designs (x to a disease the an called temperature experiment leaves (y) leaves diagram with a of the which at An agricultural greenhouse she different monitors affects the temperatures. 70 72 74 76 78 80 12.3 9.5 7.7 6.1 4.3 2.3 °F) diseased in occurring blight. regression line passing through point. equation your of equation the to regression estimate the line. number of diseased leaves 75 °F . Market sales see scatter the risk diseased of mean b at a at to She of Temperature a are research figures Price for of new (thousands Sales of new real estate homes of homes this the mean house b Find the mean number c Draw the mean d Find e Use the different year Find scatter of £) a a investments reveals prices the over following the past year. 160 180 200 220 240 260 280 126 103 82 75 82 40 20 price. of diagram sales. with a regression line passing through point. equation your of equation the to regression estimate the line. number of new homes Extension material Worksheet 10 bivariate priced at £230 000 Understanding Example A study years can 18 of r un was the were on CD: More analysis sold. regression line was a that - done young one to investigate person kilometre. collected. The and Data the the time from equation relationship of y in minutes children the between in between regression the which the line the ages was age of x in child 7 found The and to the be y-intercept height when x = of 0, is the and line might 1 y x. = 20 Inter pret the slope and not y-intercept. always have a 2 meaning. with your Be careful interpretation Answer of 1 In the context of the question, The slope is . What this means can say that, on average, as Sometimes ages one year their time the value a that child intercept. is 2 we the for ever y increase of 1 in x there x = 0 is impossible to 1 or is r un a kilometre goes down by a decrease of in represents y. 30 2 a seconds (half a dangerous minute). extrapolation For is this not question, relevant, children the since cannot run y-intercept 0-year-old one The y-intercept that when x is is 0, 20, y is which means the range of outside the data. 20. kilometre. Chapter Example A biologist trees She x per wants calculates State the to hectare the study and the the equation gradient and relationship number the of the of between birds y per regression y-intercept and the number of hectare. line to inter pret be y = 8 + 5.4x. them. Note that all these interpretations follow Answer a The slope expect The an is y-intercept birds per and 1 each x She 2 A them a of police par ticular homework up with chief = equation A of per is wants + y group The additional per an tree, you can hectare. area with no trees averages 8 not the to x a relevant, that same student of has the be the with the been y = is the and does why . per of = 40 between a days week. line y of of number relationship convicted are number the regression crime – 0.3x the and the knows. 0.5 + relationship person on spor ts person to data explain plays investigate person and y-intercept collected equation person up If has found x slope smokes 6x between per day the and number the of number of sick. the equation of the reg ression line 2.4x y of exam of came the wants to his to shop regression mathematics investigate and each line is y science year = –5 the number of x. + teachers 100x wished to compare scores. science regression salesman that equation their a the comes the that researching year customers A was skateboard The y cigarettes doctor 7 ever y birds that student the criminals doctor what teacher of y for means relevant. number days if times The 5 state of A that additional which number packs 4 y came The 3 means 5.4 score line Bivariate analysis The gradient line is which x science year hours 8, scenario, social per is of 0D inter pret A This hectare. Exercise For 5.4. average y y = and –10 the + mathematics 0.8x score x gave the pattern: the y of the amount increases increases by 1 by when unit. . The Least term contexts. between regression The the but shorter than height the him; of sons is Let the us and visit is a the illustrate of best fit is then for to a to 1.0. A tends We can mean the one ‘by father have of problem constr uct mean draw to taller have than mean. again. sons him. The We term scatter a line know number line of of that years diagram Inaccuracies the of fitting. the draw point. to a other related, tends the to relationship are sons curve and the two between point point differently towards) sorts Pisa The tall to (moves of quite examine sons. correlation tower. drawn and many tower positive have used than regresses find statistics father through only in first less used data, line) we is short the regression fathers leaning of the (regression because now strong, lean a used was of slope ‘regression’ there is method heights course, The squares best to fit occur through and the line eye’. y There is another involving way to improve our line, actual residuals data point (x y ) i Residual = y – i predicted data i y p point (x p 0 ➔ A the The graph residual above is residual the the of is a ver tical distance regression positive if the between a data point and equation. data point y is graph. residual is negative if the data point is residual below Negative the ) p x Positive The y residual graph. Zero The residual through the is 0 only data when the graph point. 0 The residual passes equation of the regression line x of yonx y The least squares regression line uses our previous formula (3, 5) 5 y – y = m(x – x 1 ), but now uses the method of least squares to 1 r 4 find a suitable value for the slope, m (1, 3) 3 ➔ The least squares regression line is the one that has p the 2 smallest possible value for the sum of the squares of q the 1 residuals. (2, 1) 2 In the diagram we aim to make p 2 + q r x 0 2 + as close to zero as 1 2 3 4 5 possible. Chapter A rather complicated formula emerges: The earliest the The formula for of regression finding the gradient, or slope method line of regression least squares was that was (m) published a form of by Legendre in 1805, and is: by Gauss four years later . Legendre S xy m ➔ = , and where Gauss both applied the method 2 (S ) x to the problem astronomical (∑ S = xy x y )(∑ determining , obser vations, from the orbits ) and xy − ∑ of of bodies about the Sun. n 2 2 (S (∑ 2 ) = x ∑ x x ) ∑ is n ‘S’ an Example the and data. least regression diagram squares line on Greek regression through page the formula points (1, 3), to find (2, 1), the and equation (3, 5) of from is letter used instruction the Use the − ∑ xy sum as to sum means of all the xy of regression values. the the 345. Answer (∑ S = xy x )(∑ y ) 2 x xy ∑ y xy The x ter ms in The line of on n 6 = × 1 3 3 1 2 1 2 4 the for mula y x, which can 9 20 be used to estimate y 3 = 3 5 15 9 6 9 20 14 given 2 2 (∑ 2 x The ) = x ∑ of ) each 2 (S sum x x column n 2 6 = 14 3 = The line 2 equation of the regression is S xy y – y = 2 (S x ( x x ) ) 2 y – 3 = (x – 2) The mean point ( x , y ) is (2, 3). 2 y Now = x you + 1 have regression line seen how works, the from formula now on for you the can equation use your of the GDC to find it. See GDC Sections ➔ Y ou should use your GDC to find the equation of the 5.16. regression line Bivariate analysis in examinations. Chapter 5.15 17, and Example The table in US to twelve of shows dollars Use a this Write c Use distance Changi in km air por t, and airfares Distance Fare Singapore, 576 178 370 138 612 94 1216 278 409 158 1502 258 946 198 998 188 189 98 787 179 210 138 737 98 destinations. your b the from GDC data down your 1000 km to with the sketch the a scatter line of best equation of your equation to estimate diagram fit. line the of cost best of fit. a flight. Answers a GDC help on CD: demonstrations Plus and GDCs y b = 0.117x + 83.3 You will answers cost c = (0.117 = × 1000) + Cost 83.3 = three $(0.117 Dollars $200.30 usually to and have to round significant × distance cents two Casio are on Alternative for the TI-84 FX-9860GII the CD. your figures. + 83.3) decimal places. Exercise Y ou 0E should use your GDC for all of medicine by a this exercise. It 1 A patient is given concentration intervals. will exist The in his blood doctors between the is believe drip feed measured that a at linear and its the hourly this the relationship variables. x (hours) 0 1 2 3 4 5 a Show the b Write down c Find the y 2.4 data on the 4.3 a 5.0 scatter equation concentration of 6.9 9.1 diagram of the sensible – relationship value The after we from 8 don’t will process to predict hours know continue of outside tr ying the from whether to to range be predict of your 6 11.4 with be equation data Concentration not concentration linear . a T ime would a is called extrapolation 13.5 line of best fit. line. medicine in the blood after 3.5 hours. Chapter 2 The of table below Malaysian shows the Ringgits for value the of first Jai’s seven car in years thousands after it was purchased. Age (yrs) Cost a (MYR Show best 1000) the price 0 1 2 3 4 5 6 7 30 25 21 19 18 15 12 10 of the car on a scatter diagram with a line of fit. b Write down c Estimate the equation of the regression line. 1 the cost of his car after 4 years. 2 d Suppose Jai equation 50 3 The and takes cannot good be care used to of the car. estimate Explain the cost why of the the car after years. table the below number shows of hours Person Months ten people that who they bought exercised gym in the membership past week. Nat Nick Nit Noi Nancy Norm Nada Ned New Nat 7 8 9 1 5 12 2 10 4 6 5 3 5 10 5 3 8 2 8 7 of membership Hours of a Show b Find c If Nino Could Naja 4 Sarah’s Their Age he use diagram height, HEIGHT = height of a the diagram regression member last for 2 years concer ned has 3 the to that she following 60 86 90 91 94 95 showed hormone), a least + and the strong he positive squares 0.3833 is 50 best fit. how uses the The old if shor t of many for her Sarah’s line doctor there and hours why . association regression prediction, many Explain regression AGE. years doctor’s how seems record 57 she of estimate membership? 51 71.95 line line. estimate 48 when a months, 36 a with week. equation after and Check scatter your are (cm) and a exercised you prediction. was between found wants is no line to to predict inter vention for then age. height: this comment on procedure. Revisit the a Find b Draw the been (months) (growth 5 has parents Sarah’s this on equation exercised A scatter be data paediatrician Height age the the hours d exercise data the a scatter mean c Find d Use from mean the leaning diagram tower of Pisa. with a regression line passing point. equation your the point. of equation Bivariate analysis to the regression estimate the line. lean in 1990. through . Up to Measuring this point relationship determined We have then line for Now it as positive called the will the used seek a scatter between or two negative; correlation equation prediction we have (correlation) also found we correlation of the diagram to variables. zero weak, regression if see We there is moderate line of y if there is a have no or on correlation. strong. x and We used the pur poses. to classify the strength of the correlation Karl numerically . There are several scales that are in use; we will study Pearson 1936) correlation coefficient developed by Karl founded rst statistics The Pearson product moment correlation byr) variables X is a measure of the It is of widely linear Y, used giving in the dependence a value correlation sciences between between as a two between +1 measure and of −1 the in coefficient is used to strength variables. determine how nearly the relationship fall on a straight line, or how nearly linear they are. the A not linear , will have a regression coefficient of r = 1.000. the 0.01 physical or gives better. us margin the of sciences That we means confidence to would that say a like to have coefficient that a of a ‘confidence r = relationship is 0.990 or linear level’ of higher within a not coefcient adequately represent of the the y between the r-value Pearson’ s the from correlation coefcient indicates strength relationship two x 0 positive Here r = r are variables. y The correlation strength relationship 0.01%. y Perfect this Normally does in then perfect correlation correlation variables the is points 1911. inclusive. between regression College two In The depar tment University London and university coecient at (denoted the Pearson. world’ s ➔ (1857– a = linear x 0 No correlation r = 0 some negative correlation more data sets and their r the sets. x 0 Perfect 1 data of between r = linear −1 values: 0.7 r = 0.3 Chapter For negative correlation, the value of r is also negative r r ➔ The formula = = –0.3 –0.7 for finding Pearson’s correlation coefficient is S xy r = S S x y where 2 (∑ S = xy x )(∑ y 2 xy − ∑ (∑ ) , S = ∑ x x x ) − Y ou these n n the 2 (∑ 2 S = y ∑ y y ) − n ➔ A quick way to inter pret r-value 0 < 0.25 0.5 |r| ≤ < |r| < 0.75 Example Sue wants number orchids formula Plant of < |r| is: Ver y Weak 0.5 Moderate 0.75 ≤ weak Strong 1 to determine spoons grown to ≤ ≤ r-value Correlation 0.25 |r| the of from inter pret Spoons of food a the plant plant. the Use she of the uses correlation and Pearson’s the extra correlation Increase of in the orchids A 1 2 B 2 3 C 3 8 D 4 7 Bivariate analysis number the of coefficient number y { between relationship. plant x strength food should recognise and Continued on next page formulae previous from section. Y ou should use your Answer GDC 2 (∑ S = ∑ xy x )(∑ y calculater 2 Plant x y xy x y A 1 2 2 1 4 B 2 3 6 4 9 in ) the examinations. xy n 10 × 20 60 − = to We have formula shown and the table = 10 4 C 3 8 24 9 64 D 4 7 28 16 49 here to help understand you where the 2 value 2 S x x x Total 10 20 60 30 comes from. 126 See GDC Chapter 17, n Section 5.16. 2 10 = 30 5 4 2 2 S y y y n 2 20 126 26 4 Regression S r = = S ≈ S x 5 y correlation 0.877 positive correlation means the number of spoons of help on CD: Alternative different sets to there see for the the number of Plus and GDCs extra orchids Casio r-value if are on the CD. a you 0.877 to explore other. are to For predict are example, positively expectancy correlated, we know correlated. who is likely So to we that when succeed can IB predict scores one and based college college admission at universities, their on students with high IB formulae appear officials they want will scores. statistical methods complicated at first sight, making useful and evaluating the r-value are quite straightforward. would for the analyzing table a achievement be the and GDP. the Which While between correlation. variables choose the indicates countr y’ s two For might increases. of life If data, may connection. example, relationship strong of FX-9860GII wish The two TI-84 be increases, compare plant demonstrations food to that GDC as allow 26 you A and 10 xy From business this performance? point on we will be using technology to find the r-value. Chapter Exercise 1 Nine their 0F students results. between the a Find two French the sets and r-value of a Spanish and test. describe the The C D E F G H I French 56 56 65 65 50 25 87 44 35 Spanish 87 91 85 91 75 28 92 66 58 thinks that social income psychologist and gives scores. B A table correlation A Subject 2 sat education. She there found is that a correlation people with Y ou between can that higher people years income have more years of education. The results of her shown Years 3 (thousand of Find b What can c What does a shows $) A B C D E F G H I J 125 100 40 35 41 29 35 24 50 60 19 20 16 16 18 12 14 12 16 17 education a Does the car the with it more education higher income. below . Person Income of phrase sur vey have are also r-value. you say the stop age about sign more (in of the the slowly months) strength r-value as of it a the correlation? indicate? gets car of older? and its The table stopping below distance (in 1 metres) Age from a speed (months) of 40 km h 9 15 24 30 38 46 53 60 64 76 28.4 29.3 37.6 36.2 36.5 35.3 36.2 44.1 44.8 47.2 Stopping distance 4 (m) a Find the b What c Describe happens Kelly has focus on on the her to the stopping strength always school Kelly’s r-value. been studies. grades of told Kelly first, the and to distance as the car gets older? correlation. stop wants chatting to decides see to if on the there sur vey 10 computer will be any friends. and effect Here are results. An GPA 3.1 2.4 2.0 3.8 2.2 3.4 2.9 3.2 3.7 3.5 14 16 20 7 25 9 15 13 4 14 A grade points, Chat a B is wor th is 3 4 points, time a C is 2 points, a D is 0 1 (h/week) point, and points. a Find b Describe c the Based F average r-value. on the the grade is grade point sur vey , decreased? Bivariate analysis called the correlation. would Kelly’s grade increase if the chat GPA. time an The average, 5 Mo get 10 had on always with friends been some to see told work, the to and effect stop so on playing he computer decided GPA. The to games conduct results are a in and sur vey the of table below . GPA Game 2.7 3.8 1.5 3.6 2.2 3.8 2.0 1.9 2.5 3.0 10 24 25 17 5 26 14 30 22 7 time (h/week) a Find b Describe c Based time the r-value. the on correlation. the sur vey , would Mo’s grade increase if his game Extension material Worksheet 10 bivariate 6 Find on CD: decreased? and inter pret Review the r-value for the leaning tower of Pisa - More analysis data. exercise ✗ 1 Phrases i, between i High ii Low iii No iv Low v High Which ii, iii, two iv, and v represent positive positive of the correlation linear linear correlation correlation correlation negative linear negative phrase variables best shown correlation linear in correlation represents each of the the relationship scatter between diagrams the two below? y y a b 10 10 8 8 6 6 4 4 2 2 0 0 x 2 c descriptions variables: 4 6 8 10 x 2 4 6 8 10 2 4 6 8 10 y y d 10 10 8 8 6 6 4 4 2 2 0 x 2 4 6 8 10 0 x Chapter EXAM-STYLE y QUESTIONS 60 2 The and following the table number of gives the amount kilometres of traveled fuel after in a car’s filling the fuel tank, tank. )sertil( Distance Amount 220 tank 500 680 850 (km) of 20 fuel 55 in 276 leuF 0 traveled 40 43 30 24 10 6 (litres) 0 x 200 a Copy the scatter diagram and plot the remaining 400 Distance The mean amount on the of Sketch c A the This table took them Age T ime a Plot b Find c Draw d How to to 2 28 of best fit left the r un in through Use the ages of your ten the line mean of point. best policemen fit to estimate the and the time that it 100 m. 45 45 50 10.9 11.1 10.8 12.0 11.2 12.1 12.6 13 12.7 13.6 data a on mean line the of a scatter age and best would fit you diagram. the mean through expect a point. 30-year-old policeman to take exercise QUESTIONS 6 the number of push-ups 3 4 5 6 Push-ups 7 8 5 3 2 2 a scatter a Show the b What happens points c Find the equation d Find the r-value heights (m) that David can do each minutes. 2 and h (kg) on to the use of regression it a to along push-ups a the line time of best fit. increases? line. describe sample with as of the 11 relationship. students are: 1.47 1.54 1.56 1.59 1.63 1.66 1.67 1.69 1.74 1.81 52 50 67 62 69 74 59 87 77 73 67 regression regression Bivariate analysis the of 1.36 the height of and diagram number weights w down whose mean 100 m? shows the time. the 1 Use plotted 39 for b is 35 table Write point 32 long a This mean 25 the Weight the tank. Minutes The litres. and 24 the Height is y 421 km, 23 r un minute tank is x 22 EXAM-STYLE The the 350 km. fuel shows Review 1 line of in traveled (km) diagram. traveled amount 3 fuel scatter b car distance 600 points. is line 1.6 m. to line of w estimate on the h. weight of someone EXAM-STYLE 3 A psychologist IQ of a child the IQ of a sample a Write b Find c Use a down the the The and of 8 your children mother. and She mothers: 103 108 111 123 94 96 89 102 98 94 116 117 correlation of to took line line IQ predict between x the IQ of the a, explain how accurate mathematics are of Test given tests. 2 We from Test 72 32 68 55 80 45 77 Test 2 31 38 16 34 27 41 22 37 Describe c Copy on your Find e If the tend that it a Height was y (cm) Plot these represent 2 cm on b Write c Plot d i e Find the f Draw g Using 1. ‘Students score of a diagram. best score will on get with Test a high score 2’. fit. of in measured 40 in Test for Test 1, what can 2? the first 8 weeks 3 4 5 6 7 8 23.5 25 26.5 27 28.5 31.5 34.5 36 37.5 of values on the line the the on of on a scatter horizontal diagram axis and taking 1cm to 1cm to represent axis. value point of on the the mean scatter correlation this equation your was know 2 down the line student to 1 Comment ii ……. the like 0 mean Write your sentence achieved ver tical down the think diagram. from a plant week the you bought: pairs 1 scatter the of this pot x Week a have student of when to equation predict height from a 1 on correlation complete another we The and Test d results the of below: 54 Plot y mother would 1 b and x. estimate result results on be. two the to coefficient y 100. par t to of Test a measures 98 likely percentage their between 94 answer could of relationship 91 an is IQ the 87 the with investigate the regression students we to regression estimate Eight if y IQ child Using this x IQ Mother’s 5 wants the Child’s 4 QUESTIONS of Name coefficient, r, for it L. these readings. result. the regression regression equation point. diagram. on estimate the the line of scatter height y on x. diagram. of the plant after 1 4 weeks. 2 h DJ tall uses after the 30 equation weeks. to claim Comment that on a his plant would be 62.8 cm claim. Chapter EXAM-STYLE 6 QUESTIONS Personality 10 teenagers. called is to around. bossy average They The of also repor ted those items a is is a stealing is a of a group personality measure ask the of behaviors problems behavior of about person how how is. variable nice that cheerful, Each of person stubbor n, teenager’s repor ted. measure various swearing, behavior This the assessed questions cooperative created on cheating, The and studied researchers ‘agreeableness’. be polite, of researchers behavior in and the last problems. six fighting. repor ted. The months, Each youths including teenager’s sum Agreeableness Behavior factor problems Par ticipant George 4.3 5 Bill 3.0 22 Ronald 3.4 10 Jimmy 3.3 12 Gerald 2.9 23 Laura 4.0 21 Hilar y 4.7 2 Nancy 2.4 35 Eleanor 2.9 12 Elizabeth 4.7 4 a Constr uct b What c Find d Describe e Copy the the and Write g Michelle behavior produces nine a show agreeableness the factor regression line. increases? on the to sentence have _________ equation absent her for ‘Teenagers of the the behavior regression behavior agreeableness. who more problems’. line. problems Estimate were her questions score for but the problems. clothing are the factor y total shown recorded production in the the cost y following number x dollars. of The coats it results 26 44 65 43 50 31 68 46 57 y 400 582 784 625 699 448 870 537 724 Write Use down your the equation regression line as b Inter pret the meaning c Estimate the cost d The factor y number order to of sells coats make Bivariate analysis a of the of a the of i boxes the profit. for to the producing that regression model answer the ii of y on x. following: the y-intercept. coats. $19.99 factor y line gradient 70 for table. x a the was and days and correlation. tended 4.5 day , the complete down scored as diagram r-value. f Each scatter happens agreeable 7 a each. should Find produce the in smallest one day in CHAPTER ● Bivariate pairs of Scatter analysis The ● To draw concer ned (x, y) in (also diagrams between relationship graph. is a with data the relationships between set. diagrams relationship ● SUMMARY variables Scatter ● 10 a two between scatter The called variables two diagram patter n scatter that variables plot formed plots) by the the both is (x, to to investigate the same the possible ‘event’. their correlation values can used relate called y) dots are give from us the some data table as indication of dots on a the correlation. The independent variable on the variable ver tical should be on the horizontal axis with the dependent axis. y elbairav tnednepeD 0 independent x variable ● A general upward ● A general downward ● Scattered ● A correlation the The ● A points line the trend with no between of of best best association then be used fit or in patter n the trend two dots patter n may data of of indicate sets does shows posi tive dots shows negative correlation not correlation. close necessarily correlation. to zero mean that one causes to the line rises ■ If the line falls ■ Strong the Weak of positive clustered near two from and best drawn variables on and a to scatter show diagram the to trend. find This the line direction of best fit of can left left to to right right negative then then there there correlations is is a posi tive a negative have data correlation. correlation. points ver y close fit. and or line is predictions. from positive line trend make If to fit between ■ ■ in other. line an trend negative on the correlations line of best have data points that are not fit. Continued on next Chapter page ● To draw the a line number below the one point and is mean of of line. for best points An the the by eye the draw line improvement line calculated of fit above by to pass finding line that the have a through. This is mean of will balance number to the is a with of reference points point: the mean point the x-values and the y-values. y (x, y) 0 ● x The can equation be Least ● A used of for the is of prediction squares residual line the best fit, also called the regression line , pur poses. regression ver tical distance between a data point and the graph of a regression equation. ● The the ● least sum The squares of the formula regression squares for of finding line the the is the one that has the smallest possible value for residuals. gradient, or slope (m) of a regression line is S xy m = , where 2 (S ) x 2 (∑ S = xy ∑ x )(∑ y ) 2 and xy − (S ) (∑ 2 = x ∑ x Y ou should use your ) − n n ● x GDC to find the equation of the regression line in examinations. Continued Bivariate analysis on next page Measuring ● The of Pearson the correlation product correlation inclusive. It is dependence moment between widely between used two two in correlation variables X the sciences coecient and as a Y, (denoted giving measure a of value the byr) is a between strength of measure +1 and −1 linear variables. S xy ● The formula for finding Pearson’s correlation coefficient is r = S S x y where 2 2 (∑ S = ∑ xy x )(∑ y xy − ) (∑ 2 , S = x ∑ x − A quick way to r-value 0 < 0.25 0.5 |r| ≤ < |r| < 0.75 ≤ ≤ < |r| the r-value S = ∑ y y ) − n is: Correlation 0.25 |r| inter pret 2 and n (∑ ) y n ● x 0.5 0.75 ≤ 1 Ver y weak Weak Moderate Strong Chapter Theory of knowledge Correlation shows Correlation For example, is Causation For ■ If we nd a and high that strong pregnant weight, how the when example, bir th as the because two time correlation of causation? two one variables you go to between at should heavier closely value achievement women or age tr y babies to directly bed a 24, variables increases, baby’ s boost achieve their more the weight we with does affect affects should var y so the each each other. other. other. number of hours sleep. at suggest baby’ s you EFFECT bir th highly? EFFECT Sometimes always. It correlated between a is cause easy are two and to also effect assume that connected events does are not closely events causally . mean related, that But that are but not closely correlation one has caused the CAUSE other. For example, if your cat stays out all night and then gets A gets sick night be a because may vir us not or it stays cause the out all night. sickness. The But being cause is outside more necess What h ■ knowledge: Correlati or ation? asks questions: relationship p exists of to of ■ w What etween v ri l connects or separates them from other? each correlation variab bacteria. these Theory all likely Correlation EFFECT cau Which is ● Bullying ● Stress causal harms and mental which is correlated? ● health. Watching too television of watching major spor ting be hazardous The temperature to the and real the number of vendors out on that TV raises blood being violent Surgeons pressure with video game skills perform in simulated surger y. day. ● ● people life. ice better cream to on hear t. ● ● leads violence events in can much in Swedish speakers are obese healthier than Dutch adults. speakers. ● Deep-voiced men have Anscombe's Anscombe’s caution without Quartet against first is children. Quartet a applying generating more group of four individual more data sets statistical that provide methods to a useful ncis Fra data be com Ans evidence. (191 F ind the mean variance Set y and x, the the mean r-value 1 of for Set y, the each variance data of x and 01) tish Bri the an. istici stat set. 2 Set 3 Set 4 x y x y x y x y 4 4.26 4 3.1 4 5.39 8 6.58 5 5.68 5 4.74 5 5.73 8 5.76 6 7.24 6 6.13 6 6.08 8 7.71 7 4.82 7 7.26 7 6.42 8 8.84 8 6.95 8 8.14 8 6.77 8 8.47 9 8.81 9 8.77 9 7.11 8 7.04 10 8.04 10 9.14 10 7.46 8 5.25 11 8.33 11 9.26 11 7.81 8 5.56 12 10.84 12 9.13 12 8.15 8 7.91 13 7.58 13 8.74 13 12.74 8 6.89 14 9.96 14 8.1 14 8.84 19 12.5 Write and of of 8-20 down their Using each you regression your set what GDC, of think lines sketch points on a the will the graphs look graph different Draw Explain the regression line on each graph. like. what you notice. of graph. Chapter Trigonometry CHAPTER OBJECTIVES: 3.1 The circle: 3.2 Denition radian measures of angles; length of an arc; area of a sector sin cos θ of and sin θ in terms of the unit circle; denition of tan θ as ; cos exact values of trigonometric ratios of 0, , 6 2 3.3 The Pythagorean 3.6 Solution of identity triangles; the , and , 4 3 their multiples. 2 2 θ cos + cosine sin r ule; θ = the 1 sine rule, including the ambiguous 1 case; area of a triangle ab sin C; applications 2 Before Y ou 1 you should Use start know proper ties Pythagoras’ of how to: triangles, Skills including 1 check Find the value the x in each diagram. theorem. a e.g. Find of value of b x x° (2x)° 41° 96° in each diagram. x° (x x° – 49° a x° + 96° + x° = 180° 38° = 180° 38° x = – 96° – 38° 46° c ABC b is isosceles, so ∠A = d x° ∠C (4x)° B ∠A + ∠B + ∠C = 180° = 180° (x x° + 53° + x° + 20)° 53° 56° 2x° = 180° – 53° = 127° x = 63.5° x° A C e c Using f Pythagoras, x 2 x 2 = 6 2.4 2 + 9 x 6 24 5.6 19 9 x Trigonometry 20)° Sometimes tree or a directly . and For the a method a tree or also rock find the of these distance reference on formation. angle dimensions width a (such canyon) dimensions as the that we using height can’t of a measure trigonometr y triangulation. accurately the know the can find of to or of to point measures and need Sur veyors example, needs as we mountain the the far Then, distance formed across by a side canyon, of standing between these points the on a sur veyor canyon, the near two known and the such side, he points, point on the Some far side. Using trigonometr y , this is enough information to use the distance the far to the other side, without ever having to cross mathematicians find the phrase to ‘measure side of the canyon. instead of of angle’ ‘size of angle’. . This sizes then Right-angled chapter of star ts angles extends and to trigonometr y . by looking side areas triangle of at lengths the of triangles trigonometry relationships right-angled and real-life between triangles, the and applications of Some ‘right of people say triangle’ instead right-angled triangle. Chapter Star t by looking at the right-angled triangle with ver tices at the Angles points A, B and C. The angles at these ver tices are can described Â, ˆ B ˆ C, and be called in various respectively . A The side AB, the side opposite the right- ways. This could be ABC angle, is called the of hypotenuse triangle called the angle at the ˆ A c right-angled could ˆ C A B; ∠CAB. also can labeled with B a this A; ∠BAC; Angles be Greek In called ˆ B A C; C be triangle. b triangle, notice that the side labeled a (side BC ) is opposite letters like θ Â, (theta). the side AB ) is their labeled opposite opposite b (side ˆ C. It at these is is opposite convenient to ˆ B, and identify the side sides in labeled relation c (side to angles. Trigonometric Look AC ) two ratios right-angled triangles. D A 59° 59° 31° 31° B C ABC and DEF is DEF E each have F angles measuring 59°, 31° and 90°. Some larger than ABC. Triangles with the same three the are called triangles , simi lar and their corresponding sides are in two of a right-angled propor tions. triangle of For ABC and the the legs triangle. AC BC DF , = AB any their AB similar sides will corresponding The fact define These that the ratios ● any the be in the the sides of var y DF regardless same be right-angled how ratios. in In large other propor tion similar according longest side the triangles ratios to to the of small words, each form – sine, sizes or are, their other. equal cosine the they ratios and angles helps us tangent. in the triangles. opposite side side ● the triangle (often the opposite (sometimes side next (sometimes a triangle. abbreviated right to h or H) is the longest side angle (hypotenuse) h o ● of = trigonometric hypotenuse is the will is EF and AC triangles, right-angled and BC , DE sides three right-angled In EF = and DE The DEF: hypotenuse For call shor test the sides same textbooks angles Trigonometry to the angle marked θ abbreviated the angle θ abbreviated to o is to a or called or A) is called the opposite O) the i adjacent side a (adjacent) (opposite) ➔ For any right-angled triangle opposite θ sine with A angle θ : an mnemonic made-up O is word a or = hypotenuse phrase H that remember adjacent helps a list you or a A H cosine θ = O formula. hypotenuse H Remember opposite with tangent θ these i O the mnemonic = A adjacent Look at this right-angled A SOH-CAH-TOA triangle, with  highlighted. We BC A sin A AB AC c cos A A tan b AB c BC a = AC astronomer Ar yabhata, about use trigonometric ratios to find unknown side lengths in right-angled circled between sine, cosine and in ABC : invent a sin the and the different tangent orbits. triangle India triangles. Ear th In that planets stars Relation in CE, and Sun, angles born 476 believed can these ratios. b in Y ou for = B tan and trigonometric The a C sin, c cos b the abbreviations = = use a in He began to trigonometr y order to calculate = c the distances from b planets cos to the Ear th. = A c a sin i a c c so = = b cos b b c a but tan C = a B b sin = tan so cos sin ➔ tan cos Although Example mathematicians studied For this triangle, find the length of side have triangles a. for thousands years, 34° the of term ‘trigonometr y’ was 6 rst by used Pitiscus a { Continued in 1595 Bar tholomaeus (German, 1561–1613). on next page Chapter Be sure you are in Answer opposite a degree tan 34° = = Use adjacent the = 6 tangent ratio. 6 The a mode side opposite the angle of 34° tan 34° T o is the opposite side, and the change to degree side and a = 6 tan 34° ≈ 4.05 adjacent to 34° has length 6. choose You can find the value of tan & using your 5: Settings 34° Status 2:Settings GDC. 1:General Use the move To enter tan μ press and then select to select tan. key Angle and Degree. and then to Press select 4:Current If you know the and you want you will need lengths to find of the the sizes sides of of the a right-angled angles of the triangle triangle, –1 –1 use the inverse this triangle. trigonometric functions sin , –1 and cos to tan Example GDC Find the size ˆ B of in help on CD: demonstrations Plus and GDCs Casio are on Alternative for the the CD. 9 cm 5 cm −1 sin is 'arc called sine,' −1 B cos is 'arc cos' is 'arc tan' −1 tan Answer opposite sin B 5 = = hypotenuse The side opposite ˆ B has length of 9 5 cm of and 9 cm. the Use hypotenuse the sine has a length ratio. ⎛ 5 ⎞ ˆ B –1 –1 = sin ⎜ ⎝ ⎟ 9 ≈ To 33.7° enter sin press μ and then select ⎠ –1 sin In this exercise, missing angles calculator is and set Trigonometry you in will side be solving lengths). DEGREE right-angled Always mode. make triangles sure that (finding your TI-84 FX-9860GII Exercise For each A question, use the diagram and the information given to b A find all your the unknown answers correct angles to 3 and sides. significant All lengths figures are where in cm. C Give necessar y . a c 1 a = 3 c 5 a 7 If 12, = c 20 ˆ B = 4.5, = = 11, Â, 55° = 35° 2 b = 37,  4 b = 48, c 6 a = 8.5, = = b 40° 60 = B 9.7 x 2 a of = x, 2x, and Special Look b at = 5x the – 1 angles and  c isosceles 1 + 1 (x ∈ ) find the ∈ means that x is value an integer . triangles right-angled To C x ˆ B and right-angled this = solve triangle. the triangle, you need to find the A length AB, Using 2 angles Pythagoras’ 2 + 1 and 1 2 = c  ˆ B and theorem 2 , so c = 2, and c = AB = 1 Using c the tangent BC tan A ratio = = AC = 1 –1  B This and Now look at the values of = is ˆ B the tan an = (1) = 45° isosceles triangle, so  = ˆ B, 45°. trigonometric ratios of this triangle. 1 2 45° ➔ sin 45° = = 2 2 1 cos 45° = = 2 45° 1 tan 45° = = 1 1 Now half To look of 2 1 an solve Using a this right-angled equilateral the triangle, Pythagoras’ 2 + at 2 = 2 triangle, which so a you need theorem = 1 A triangle. to find BC, 3, and a  and ˆ B. gives 2 , C is = BC = 3 a 2 B Chapter Using the cosine AC cos A ratio, = = AB ⎛ ⎞ –1  = cos ⎜ ⎝ ˆ B = 180° Here are = ⎟ – 90° the 60° ⎠ – 60° values = of 30° all the trigonometric ratios for this 30°–60°–90° triangle. 1 ➔ sin 30° = sin 60° = cos 30° 60° = cos 60° = √3 2 3 3 tan 30° = = tan Example Find the 60° = 30° = 3 3 1 value exact of x in this triangle. When an answer you 60° exact is asked should for leave the 5 cm square in your not root or answer change it radical and to a x rounded Square Answer x tan 60° = 5 Exercise 1 Use the perfect 3 cm called diagram to a a = 12, b b = 9, c c d b = 6, c e a = , solve are in each right-angled triangle. Give are exact b c  4.5, = = ˆ B = C 24 the c all means unknown and angles. The diagram sides a = = exact c 60° will not B 10 values of x, y and z P z x 30° Q Trigonometry here nd 45° 8 squares cm. always Find not surds. 'Solve' Lengths A 2 are B answers. = of that 3 5 x roots numbers = = decimal. 8 R y S be to scale ABC 3 has  = ˆ C 60°, = 90°, BC = x + 2, and Sketch the triangle 2 AB = – x 4. rst. a Find the exact value b Find the exact length Triangle 4 ABC has ˆ B = of x. of side ˆ C 45°, = AC 90°, AC = 4x – 1 and 65° y 2 BC = + x 2. z a Find the value of x. b Find the exact length of side AB x In 5 to the diagram 1dp. find Lengths the are in values of w, x, y and 45° z, cm. w 4 9 . Applications triangle In the last triangles how to section, using apply right-angled trigonometry you sine, these of found cosine lengths and and tangent. trigonometric ratios angles In to this in right-angled section, solve you problems will in see real-life situations. Let’s ➔ begin The with angle some of terminology . elevation is The angle of depression the is angle the ‘up’ angle from ‘down’ horizontal. from horizontal. C Angle of elevation Angle of depression A B Horizontal D Example An obser ver elevation the of nearest stands the top 100 of m the from the building base is of 65°. a building. How tall is The the angle of building, to metre? { Continued on next page Chapter Answer T Star t Let by O sketching represent obser ver on the of base represent Mark the the the the diagram. position ground B building top 65° a the of the angle of of the represent and T building. elevation. 65° B 100 O BT tan 65° = , so You are finding the height of the 100 building, BT = The the Y ou ➔ 100 tan building nearest also 65° is ≈ 214 metres need four east (E) to solve and clockwise using 40° 40° E, west of to compass from using compass points are points nor th (N), and bearings. south(S), (W). bearings give directions as angles measured nor th. compass which east tall, problems cardinal Three-figure N BT. metre. The When length 214.45... points means nor th. for W direction, 20°S, south of which you will means see 20° west. notation NW, such which nor th and as: means 45° between west. N N N N 40°E NW 40° 45° 45° 20° W 20°S S S S When 035° using which clockwise bearings means from for 35° nor th. direction, 110°, 110° you which will see notation means clockwise from such as: 270°, nor th. from 270° N which nor th. is the means Notice same as 270° that ‘due clockwise a N N 035° 110° 270° 270° 110° S Trigonometry S S bearing west’. of Example Two ships Ship A Ship B Find leave sails sails the nearest dock due on at nor th a the for bearing distance same 30 km of between 050° the time. before for ships dropping 65 km when anchor. before they dropping are anchor. stationar y , to the kilometre. Answer Sketch B the dock Ship A at 30 a A diagram. from stops Point which at A the and D represents ships ship B set sail. stops B. 65 You need to find the length AB, the 50° distance D are C B between the ships when they stationar y. There are no right-angled in diagram, triangles The the so draw them angle DBE is in. found 50° using the A The hypotenuse of each right-angled alternate triangle 30 is the path of one of angle the 65 proper ty. ships. 50° 40° angle D Add any angles you know from proper ties. E BE sin 40° = Find BE. Find DE. 65 so BE = 65 sin 40° ≈ 41.781... DE cos 40° = 65 so DE = 65 cos 40° BC = DE AC = BE C = – = 49.7928 Store these values in your GDC. 49.7928... 30 = 11.7812... 49.7929 Add B the new infor mation to the diagram. 11.7812 50° A 30 65 50° 40° D E 2 AB 2 = (49.7929...) 2 + (11.7812...) Use Pythagoras’ Use the theorem in ABC. Use so AB = .1677... values you in The ships are exact the intermediate approximately steps, 52 km apar t, values stored. to the nearest km. for the and round nal only answer . Chapter Exercise 1 B C Isosceles triangle AB = = CB ABC 15 cm, as a Find the height b Find the sizes has side AC = 10 cm and shown. of the triangle. 15 of BÂC 15 ˆ AB C and A 2 ABE as a b fits shown. Find BC the Find Give exactly 28 cm lengths the your = inside sizes and of square DE = segments ˆ AE D, of answers the ˆ EB A correct to D ABCD, C 10 8 E C 8 cm. AE and BE ˆ AE B and 28 3 sf. A 3 An obser ver sea level standing on the top of a ver tical cliff 120 B m above If sees a ship in the water at an angle of depression of a not How far is the ship from the base of the diagram cliff ? given 4 A 5 the Anya in From of angles a A then Buildings X From elevation 12 m the the and width diagonals nor th, then Find above top 70 m por t and depression her 18 mm. of tur ns the and distance rectangle. walks and another bearing 3 km from her of the ground Building apar t, what B is in Building across the the A, street height of the is angle 40°. Building If B? to to sails must and a and Y the 15 km the are point the sails top of on ship the of a on a bearing sail across on base 35 km to the roof Building of Y of retur n street Building bearing 105°. from is is 55° 35°. to each X, and How 047°. How directly Building Y of far, the tall ship and on por t? other, the The 95 m angle of angle are It of the is to two a sure side Jacob is walking north along a straight road when he spots a good check answers buildings? 9 is a field to his right on a bearing of 018°. After walking he notices the tower is now on a bearing of walking Trigonometry north, how close will he pass to the make the shor test opposite angle the and the another 066°. If tower? side is opposite he the continues to nal tower longest 240 metres idea your that smallest in by own. QUESTION bearing, apar t. due N35°W . are leaves tur ns what 8 of buildings ship 25 mm between window EXAM-STYLE 7 star t your point. elevation the length 2 km direction star ting 6 has walks the the QUESTION rectangle Find with question, drawing EXAM-STYLE is 9°. largest angle. 10 From her position at ground level, Hayley notices that the angle Unless of elevation of the top of a building is 40°. When she tells 20 metres closer to the building, the new angle of the elevation is you 11 the is A car A passenger ahead the the of traveling at angle more 12 height an of time in the at the angle a car of sees a elapse of the before the ground is level. speed bridge elevation elevation will building. constant otherwise, 55°. assume Find question moves of the a straight spanning 5°. bridge on Ten is car the seconds 17°. How passes highway . highway later, much directly under bridge? The diagram ABCDEFGH. Find these shows AD = a right 24 cm, rectangular DH = F prism, 9 cm, and HG = G 18 cm. angles. 18 a HÂD b AB E c HÂG ˆ E H 9 AGD d A . Using in The angle the coordinate axes trigonometry θ in a Car tesian coordinate system has its ver tex at the In origin, as shown in the diagram. A positive some measured anticlockwise from people use other anticlockwise x O the An are positive three angles α, β and the the that positive side. side is its the The called terminal like side. this, ver tex at the δ origin y angle called angle with Here is ini tial i of the along x-axis ‘counterclockwise’ instead of the x-axis. lies Some textbooks angle side is D 24 y and its initial y side along x-axis is standard a the said positive to be in posi tion b d O x O x O x The of rst the are four Greek alpha gamma γ α, letters alphabet beta and β, delta Chapter δ. 2 This diagram shows a circle with equation x 2 + y = 1 y B The one center unit. of the This is circle called is a at the uni t origin and its radius is y circle. i A In the Now diagram, take a the closer angle look θ at is positive. acute x 0 angles in B the first quadrant OA and OB OA = of the unit circle. 1 are radii of the unit circle so A i OB Next, = use 1 0 the right-angled acute angle triangle θ to form 1 x a BOC. y Using the trigonometric ratios in BOC, , so x = cos θ, B(cos i, sin i) y and sin , so y = sin θ 1 1 So point B has y coordinates (cos θ, sin θ). i A 0 Example Find then the exact give x C x these coordinates values to of point D, y three D significant figures. 1 59° A 0 x 1 Answer The exact (cos 59°, To 3 sf the Example In the coordinates of point D are AÔD is a positive angle. sin 59°) coordinates of D are (0.515, 0.857) Use your GDC to find the values of cos 59° and sin 59°. diagram, find the exact coordinates of point P y P 1 30° 0 A x 1 Answer ⎛ The exact coordinates of P are 3 1 , ⎜ AÔP is in the page 368 for exact 2 values of sine ⎠ quadrant. Therefore, 30° the coordinates point Trigonometry P are the first ⎟ 2 ⎝ See ⎞ ⎟ ⎜ of (cos 30°, sin 30°). and cos 30°. Exercise 1 Use the y D diagram to find the coordinates of point P for each P given value a θ = 20° b θ = 17° of θ. Give your answers to 3 significant figures. 1 (1, 0) i A 2 c θ = 60° d θ = 74° e θ = 90° Use the 0 diagram from question 1 to find the value of x θ The for the given coordinates of point P . Give your answers diagram always the nearest These 0.913) have b P (0.155, 0.988) c P (0.707, 0.707) d P (0.970, 0.242) 3 3 Use the value diagram of θ. a θ = 70° b θ = 38° not be to scale. degree. P (0.408, a will to Give to find your the area answers of to 3 coordinates been rounded signicant AOP for significant to gures. the y given figures. P The dashed line is the 1 θ c = height 24° of the triangle. (1, 0) i A θ d = 30° 0 Now look at are obtuse the second angles angles in the second (between quadrant in the 90° quadrant. and unit 180°). These Here is x y angles an obtuse angle in circle. B When you are working with obtuse they relate angles it is sometimes i 1 helpful to think of how to angles in the first A 0 quadrant (acute angles). Investigation This diagram angle of θ shows from x 1 – obtuse point B at a angles positive angle of 30° from OA, and point C at a positive OA. y F ind the What Use C value are the the of θ coordinates symmetr y of the of point unit B? circle B to write down the coordinates of i point D 30° 30° 0 C A x { Continued on next Chapter page Now look at the triangles formed by the sides OB and OC and the x-axis. y (–x y) C B (x y) 150° D F 0 EOC is triangles of A 30° E point congruent with B to FOB. hypotenuse are (x, y), coordinates of x then Both length the are 1. Y ou 30°– can coordinates of 60°– also see point C The B are (cos 30°, sin 30°), 90° that are 3 1 coordinates of point C are 2 (cos 150°, sin 150°), which are the same as the coordinates coordinates 2 the the y). or So if (–x, (–cos 30°, sin 30°), or 3 1 2 2 Draw diagrams showing 40° and 140° 25° and 155° 68° and 112° Label meet From the the the coordinates unit circle. each of the What investigation of these points do you pairs where of the angles in . the non-horizontal unit circle. sides notice? you should supplementar y angles. now understand an impor tant Supplementar y proper ty of add ➔ For supplementar y angles α and β, sin α = sin β, to will see illustrated graphically For any angle θ, sin θ = sin (180°– θ), and cos θ = – cos (180°– study θ) and This proper ty Exercise these –cos β = proper ties ➔ angles 180°. and Y ou cos α up will be useful later on. in when graphs cosine Chapter of you sine functions 13. E y 1 Use C to the for 3 diagram the given significant to find values of the θ. coordinates Give your of points B and answers figures. C a θ = 30° b θ = 57° c θ = 45° B 180°– i 1 1 i D d θ = 13° e θ = 85° Trigonometry 0 A x 2 Use the the diagram given tenth of in positions a question of point 1 C. to find Give the your value of answers θ for to each the of nearest degree. a C (–0.332, 0.943) b C (–0.955, 0.297) These have c C (–0.903, 0.429) d C (–0.769, 0.639) 3 3 Find the angle 4 that a 15° b 36° c 81° d 64° Find sine one of has the acute sin A = 0.871 b sin A = 0.436 c sin A = 0.504 d sin A = 0.5 look at the acute same and a Next, each line (to 4 sf), and state the rounded signicant to gures. obtuse sine. one with angle coordinates been obtuse value equation y = for  mx: y y = Any mx line with equation y = mx This has gradient m, and passes form the is a special through origin. of the equation y = ax + of b standard a or line y = mx + c x Now point look B in at what the first happens when the line intersects the unit circle at quadrant. y y = mx B x Chapter In A the first quadrant right-angled the triangle line is forms formed angle θ an with with the segment OB y x-axis. (par t of y the line This y = mx) illustrates as its some = mx hypotenuse. impor tant proper ties involving the right B(cos i, sin i) triangle First, and using the line y 2 theorem 1 gives 2 (cos θ) + mx Pythagoras’ 2 (sin θ) = = 1 2 . The usual way of writing (sin θ) i sin i 2 and 2 (cos θ) is 2 θ sin and θ, cos which gives x cos i 2 2 θ + cos sin Suppose you θ = 1 want to find the gradient of the line y = mx. y (x This line passes through the points gradient of a line 0), and B(sin θ, (x , y 1 you can find the ) 2 = Here , y 2 cos θ). The O(0, gradient, m, using the ) 1 coordinates 0 of points O and sin m cos The sin 0 = x B = tan θ cos 0 gradient of a line rise is run ➔ These three proper ties 2 sin 1 are tr ue for any angle θ 2 cos = 1 Proper ty sin tan 2 is For number known as 1 the = Pythagorean cos 3 also any x-axis, line the y = value mx of which m (the forms an gradient angle of the of θ line) with is Identity. the tan θ i Example Proper ty Find the the gradient of the line which forms a positive angle of 130° with Answer y = mx Gradient = tan θ 130° (1, 0) 0 The gradient tan 130° ≈ often useful calculations. x-axis. y is number x of –1.19 Trigonometry the line is You can GDC. find this value using your in 2 Example Find in the the gradient of the line shown y diagram. y = mx 60° 0 x Answer y Find y = the for med mx ‘standard by equivalent of 120° this to position’ line. The a positive angle angle obtuse 60° is angle 120°. 60° This 0 line standard The gradient for ms an angle of 120° in x of the line position. is 3 sin120° sin60° 2 = cos 120° = cos 60° 1 2 3 = Exercise 1 Find the answers = –1.73 F gradient to three of the line significant y = mx in each diagram, giving your figures. a b y y 117.5° 56.3° x 0 x y y = = mx mx c d y y 135° 42.3° 0 x y = mx x y = mx Chapter 2 Find the point P. equation Find the of the value line of θ passing to a the through nearest the origin and degree. b y y P(0.471, 0.882) P(0.674, 0.738) i i x x y y = = mx mx c d y y = mx P(–0.336, 0.942) i i x 0 x 0 y = mx P y e y f P(1.59, 3.76) i P(–0.8, 0.6) x 0 i Extension material Worksheet 11 on CD: x y = mx and . Y ou The can Look at use sine ABC. The to Angle sums differences rule trigonometry per pendicular - to solve alti tude triangles (height), h, that of are the not right-angled. triangle is AD, A BC c b h In the right-angled triangle ABD sin B = B This In gives the h = c sin B right-angled triangle ACD sin C = This gives Equate the c sin B h = b sinC values = of b sin C. Trigonometry h to give D C in B Rearranging this equation sin C gives = b The ratios side are Now of sine draw the from sin C sin B = = a equal, ➔ each altitude A ratios are of c angle to the length of the opposite equal. sin the the The as B to side again. c AC, Y ou and from should C find to AB that and these find ratios b before. sine rule This in For any ABC, where a is the length of the side opposite the is the length of the side ˆ opposite B , and c is the length of is given Formula booklet Â, that b fomula you use in the the examination. side opposite sin A ˆ C, sin B = a Y ou at can least (the one length of the a r ule and side sin c sine angle Example Find the its or b to solve opposite the size c = or b use a sin C = of A = sin B triangles side, an sin C if and you one know other the size of measurement angle). missing angles and sides in this triangle, giving your answers Be to 3 sure you are in sf. degree mode A T o 9.4 cm 98° change mode to degree press and c choose Status B 12 cm C |1: 5: Settings |2: Settings & General Use the key to Answer move Using the sin 98° sine sin r ule B ˆ You and need the to find length the angles B ˆ and C, to select Angle Degree. and c. and then Press select = 12 4: 9.4 9.4 sin sin so ˆ B Current 98 12 ˆ B 50.9 (3 sf ) –  ˆ ˆ C = 180 – B, so ˆ C = 31.1305533... The is sum of the angles in any triangle 180°. ˆ C = 31.1° sin 98° (3 sf) sin 31.13055... Use = 12 12 sin 31.13055 … c the sine rule once more to find c. c Don't round the intermediate = GDC sin 98° steps, just the nal help on CD: demonstrations ˆ for c = 6.26 cm (3 B , Alternative values for the TI-84 ˆ C and c Plus and Casio FX-9860GII sf) GDCs are on the CD. Chapter In Example 10, the triangle with A all measures Always sure check the labeled your shor test would final side is look answers opposite to like this: be the 9.4 98° 6.26 smallest angle opposite 50.9° the largest longest side is angle. 31.1° B 12 Example Find the and the triangle, C missing angles rounding your and sides answers in to 2 A this 40.5 cm decimal places. 39° C c 77° a B Answer You  = sin 180° – 77° 77° sin – 39° = , a so a = angle Â, and the lengths a and c the sine rule to find a and c. sin 77° a 37.36 cm sin 77° find = Use 40.5 to 40.5 sin 64° 64 ° = need 64° (2 dp) sin 39 ° = 40.5 c Check: 40.5 sin 39° c Shor test side (26.16) is opposite the smallest = sin 77° so c = 26.16 cm Example A of ship is 032°. How far (2 dp) angle (39°). angle (77°). Longest side (40.5) is opposite the largest sailing Later, did due the the nor th. captain ship travel The captain obser ves between that sees the these a lighthouse bearing two of 10 km the away lighthouse on is a bearing 132°. obser vations? Answer N Draw A is a the diagram position lighthouse, and to model from B is the which his situation. the second captain position. first L is spots the the position 132° B of the You lighthouse. have point A to to find point d, the distance the ship travels from B. L d 10 32° A Angle ABL = 180° – 132° = 48° { Trigonometry Continued on next page ˆ L= 180 –  sin 100° ˆ B – = 100° Ptolemy sin 48° Use = d 10 d the sine rule to find sin CE), in work 100° his sine 48° from = Almagest, values 0° to for wrote angles 90°. He 13.251.... also The ship travels Give approximately your answer to a included 13.25 km between points A and degree B of Solve similar to the accurac y. sine Exercise a sensible theorem 1 90–168 13-volume = sin d (c d. 10 rule. G each significant triangle ABC. Give your answers correct to 3 'Solve' a means nd triangle figures. A unknown all sides and angles. c b B a C a b = 24 cm, c a = 4.5 cm, e c = 5.8 cm, EXAM-STYLE 2 An Julia then her second Adam of a the a walks from 4 Use sees  = = the tree in 2 km the is 27°, 83°  ˆ B = a has r ule field due = 55° b ˆ c = 2.5 cm,  = 40°, C = 72° d b = 60, ˆ B = 15°, ˆ C = X 125° 43° on find S40°E and cm, the and length from is the of where notices far base that tree angles of sides XY she the is and is both now her as XZ standing. tree from 68.2°, 68.2° Z 20 Y She S75°E first and road? Adam’s How 20 standing flagpole 50°. to How the are From base south position. Kevin flagpole. of 3.6 cm, sine positions elevation ˆ B = 47°, triangle new and top b = QUESTION isosceles shown. 3  is position, 36°. high 35 metres is From the apar t, the angle Kevin’s on of opposite elevation position, the sides of angle of flagpole? Chapter A T riangles are often used in triangle you Left: The made up Hearst Tower in New Y ork City cannot isosceles A builder Crossbars give can structure. strengthen a rectangular frame by making diagonal form Investigation T ry to nd draw that triangle there are – corners ABC, with actually  two to triangles. ambiguous = 32°, a possible triangles = 3 cm, and triangles c that = t 5 cm. this Y ou should description: B B 5 3 5 3 32° 32° A b C A The given F ind measurements the size of the do b not angle C C describe in each a of unique the triangle. triangles (call them C 1 and C ). What is the relationship between these two angles? 2 Using This is when these known you are Example In all the given for C, nd ambiguous two sides and ABC,  possible = 40°, cases. a = 14 Give a cm, your Answer sin 40° angle case , B and and it the length AC can non-included for sometimes angle of a each triangle. happen triangle. triangle giving angles as and c = answers 20 cm. correct Solve to Use 1 triangle, dp. your degree sin C this GDC in mode. = 14 20 Round 20 sin 40° sin C = to 1 dp. = Supplementary 14 ˆ C have 66.7° the same angles sine 1 value. The ˆ C = 180° – 66.7°, 2 ˆ so C = two possible 113.3° 2 values for C give two ˆ B = 180° – 40° – 66.7° = 73.3° 1 ˆ possible values for B ˆ B = 180° – 40° – 113.3° = 26.7° 2 { Trigonometry – its and triangles. struts Right: rigid change is shape. of is architecture. Continued on next page rigidity to a B 1 And sin 40 finally, find two sin 73.3 values 14 for b cor rect to b 1 1 dp. 73.3° o 14 b 20 sin 73.3 14 = 1 o sin 140 b = 20.9 cm 1 66.7° 40° o sin 40 sin 26.7 20.9 A C 1 = 14 b 2 B o 14 b 2 sin 26.7 = 2 o sin 40 b = 9.8 cm 26.7° 2 20 14 The ambiguous case does not occur ever y time you solve a triangle. 113.3° 40° A ➔ There can be an ambiguous case when you use the sine r ule [ ● you are given two sides and a non-included acute C 9.8 if: If you 2 draw triangles ● the side two Exercise opposite given the given acute angle is the shor ter of the you Use the is what see. H given information to find the missing sides and angles of triangle ABC. Give all possible solutions with answers to 1 these do not in involve a this sides. Some 1 these angle the ambiguous dp. case. All a lengths  = are 30°, a in = cm. 4, and c = 7 b ˆ B = 50°, b = 17, and c = 21 A c Ĉ = 20°, b = 6.8, and c = 2.5 d  = 42°, a = 33, and c f  = 70°, a = 25, and b = 25 10 m e  = 70°, a = 25, and b = 28 g  = 45°, a = 22, and b = 14 ˆ B = h 56°, b = 45, and c = = 26 50 6 m E B 10 2 Look at this diagram. a Find BE, CE b Find the c Explain C and DE 17 m case of how the EXAM-STYLE 3 A at ship a is sizes distance Draw b How far c How far ship is the relates ˆ BCD, to the ˆ BDC, ˆ AB D and ˆ CB D ambiguous r ule. of due D must must is the west 20 km diagram lighthouse What diagram ˆ BCE, QUESTION a d angles EÂB, this sine sailing a of to the the on a sail ship at bearing a of time the bearing model ship again second when this the of lighthouse this are point 16 km lighthouse two a lighthouse 230°. the beyond distance the of sees situation. before sail captain from from 16 km is 16 km before the away? the ship? the apar t? Chapter . Y ou The cannot cosine use the rule sine r ule to solve triangles like these: X D 6.56 8.9 3.63 80° 13.2 Z 8.28 E F a Y A Consider In the triangle triangle ACD, ABC, with Pythagoras’ altitude theorem h from A to side BC c gives b h 2 2 b = 2 h + (a – 2 x) = 2 h + a 2 – 2ax + x B In triangle 2 + = – x C c 2 h a 2 x 2 so D ABD, 2 h x = 2 c – x 2 Substitute 2 b for 2 = in 2 c – x + a 2 = h the first equation 2 + to get 2 a – 2ax + x 2 c – 2ax x In triangle ABD, cos B , = so x = c cos B c By substituting 2 b This ➔ 2 = for + c – equation 2ac is The cosine For ABC, length side you get 2 a the x, cosB one form of the cosine rule rule where of the opposite a is side the length opposite ˆ C: ˆ B , of the and c side is the opposite length Â, of b the is Y ou 2bc·cos dot 2 a 2 = b b c 2 = 2 c a a Trigonometry also see written A, means where as the multiply. – 2bc cos A or – 2ac cos B or cosine rule is in 2 + 2 = A 2 + The 2 might 2bc cos c 2 + b – 2ab cos C the Formula booklet. Example Find a and the missing angles in this triangle. A 8.9 cm 80° 13.2 cm C a B Answer 2 a 2 = 2 13.2 + 8.9 2 a = a = – 2(13.2)(8.9) cos 80° Use the cosine rule. 2 13.2 + 8.9 − 2 (13.2 ) ( 8.9 ) cos 80° 14.6 cm sin 80° sin B Use = the sine rule. 8.9 a 8.9 sin 80° sin B = 14.6 so ˆ B = 36.9° (1dp) ˆ C = 180° When to – you 80° use rearrange ➔ – Cosine 36.9° the the 63.1° cosine formula r ule like to find angles, it is sometimes helpful this: rule b A = + c − a = B bc + c a − = A + C b − = Example Find angles A, B and C A 6.56 mm 3.63 mm B 8.28 mm C { Continued on next page Chapter Answer 2 2 ( 3.63 ) cos A + ( 2 6.56 ) ( Use 8.28 ) the cosine = 2 b ( 3.63 ) ( 2 6.56 ) cos A rule. 2 2 + c a = 2bc 2 ⎛ –1  = 2 ( 3.63 ) + ( 6.56 ) 2 ( − ⎞ 8.28) ⎜ cos ⎟ ⎜ ⎟ 2 ⎝  = 105° ( 3.63 ) ( 2 B 2 + ( 8.28 ) 2 − ( 6.56 ) = 2 rule (You use sine rule 2 3.63 8.28 could here instead.) 2 the 6.56 –1 = cos 2 so ˆ B ˆ C = = Now be Cosine ( 3.63 ) ( 8.28 ) 2 ˆ B ⎠ (3 sf) ( 3.63 ) cos 6.56 ) = 49.9° 180° – 25.1° look solved 105° – 49.9° (3 sf) again more Example Two 3.63 8.28 at Example quickly 5 using from the cosine 11.2. This problem can r ule. ships leave dock at the same time. 30 km before dropping anchor. Ship 65 km before dropping anchor. Find when Section they are stationar y , to the B Ship sails the nearest A on sails a due bearing distance nor th of between for 050° the for ships kilometre. Pythagoras’ theorem Answer is a special case of B Draw a diagram. the cosine rule. See A what happens equation to when the you 65 use 30 the cosine rule 50° with P 2 AB 2 = 2 30 +65 – 2(30)(65) × cos50° Use the 2 2 AB = = The the 30 a 2 + 65 2 ( 30 ) ( 65 ) cos50 ° 51.17 ships are nearest 51 km). Trigonometry kilometres apar t (to cosine 2 = b rule: 2 + c – 2bc cos 50° an angle of 90°. Exercise 1 Use I the given information to find all sides and angles in each There triangle.  a 2 c a e ˆ C A = = a 64°, 3.6, = for a far B C he the Ship the A what c and b and He of a the = = = 1 dp. 72 86 walks to lengths = 20, b d ˆ B = 31°, f a 45, = on a walking again get a 5 km continues stops All b 2.4 before back to port bearing the away N27°E leaves parallelogram diagonals of distance same and walk of 15 km is c to = a b are 33, = = 10, c = c many 8 km straight real-life applications triangle trigonometr y. of 41 = = 058°. another heading c and and of are metres. and 50, bearing for in 14 58 He on back. camp? QUESTIONS lengths is and then 103°. lengths Town 75, break, The Town 43, camp must the answers 4.9, = diagonals Find 5 = The Find 4 = a of EXAM-STYLE 3 your leaves bearing How b b 70°, hiker stops Give of sides from town and and sails was ship of and due 49 km. B cm the towns sails 6 Town A, between port are form an and A, in and east The 9 angle of 62°. cm. parallelogram. towns B acute the direction A C and N36°W . are 20 km apart. C. for 28 km. ships are Ship then B leaves 36 km from apart. On sailing? E 6 The Its pyramid other ABCDE faces are has a square congruent base isosceles with sides triangles 15 with cm. equal sides 24 of 24 Find cm. these angles. B ˆ A BD a C ˆ b E DC c EÂC A 15 . Look Y ou D Area at of triangle can find a triangle ABC the with area of base the b and triangle height using h. the B formula: c a h 1 area bh = 2 A In ADB, sin A = D C b , so h = c sin A 1 Substituting for h in the area formula gives area bc sin A = 2 Notice height that of in the this formula you do not need to know the triangle. Chapter ➔ The area of any triangle ABC 1 area or area = 2 Example a Find given by the formula: 1 bc sin A = is 1 ac sin B or area = 2 ab sin C 2 the area of triangle ABC C 7.8 cm 82.7° 8.4 cm A B E 2 b The area of this triangle is 50 cm . 8.2 cm Find θ angle i D 13.7 cm F Answers 1 a Area 1 ( 8.4 ) ( 7.8 ) = sin 82.7° Area = 2 ab sin C 2 2 = 32.5 cm (3 sf) 1 (8.2) (13.7 ) b sin 50 2 A 50 sin b = 8.2 cm 1 (8.2 ) (13.7 ) 2 c i 100 C = In 0.8901... (8.2 ) the rst centur y CE, (13.7 ) Hero (or Heron) of 13.7 cm 1 = sin 0.8901 a Alexandria developed a method B = 62.9 (3 sf ) different nding Exercise 1 Find the J area a of each triangle. All lengths in using lengths of c 56.5° 13.4 115° 25.1 9 6.8 8 32° d e f 7.88 86° 46 8.74 30 41 58° 10.98 Trigonometry 46° area triangle cm. 10 b 9.4 are the the of only for a the sides. 2 2 The triangle Find the shown value has an area of 100 m . θ of 15 m i 18 m 3 The triangle shown has an area 2 of 324 cm . x Find the value of x 57.4° 33.9 cm EXAM-STYLE 4 a Find b Hence, QUESTIONS the largest angle in this triangle. The command term 10.2 cm find the area of the triangle. ‘hence’ tells you to 17.2 cm use your par t 16.4 cm a to answer answer help par t from you b 2 5 The triangle Find the shown value of has an area of 30 cm . 2x + 3 x. 30° 4x + 5 2 6 The area Two Find of sides two a of triangle the Radians, Angles can be 20 mm triangle possible . is are lengths arcs measured in for . 8 mm the and and third 11 mm. side. sectors radians instead of degrees. The Why One use radians? complete arbitrar y tur n measure. is Babylonians believed 360°, but Radians, the number however, are 360 is a directly were somewhat related year to 360 and 360° measurements within a circle. In this section, you will see that to there days in hence a used represent one how revolution. radians One of by as are radian the an is dened central arc the connected angle which radius is of the arc length size subtended the the as to same length and Two sector radians area is the angle subtended equal to twice size by the an of the arc radius central with of the a length circle. A circle. central angle B B subtended 2r is r an by angle an with arc its r r i ver tex at the center i A A O O of the circle and its r r sides the passing endpoints through of the arc. θ θ = 1 = 2 radians radian Chapter One complete length to the tur n around The Therefore, is 2π the circumference the angle of circle the is subtended circumference which by an arc equal in circle. subtends the = 2πr circumference of the circle radians. Arc length = circumference = 2πr r i Any = 2r radians central length of angle the arc in a the angle ➔ Arc length = angle r is the a fraction subtends as a of 2π, so fraction you of can the calculate the circumference. rθ = radius measured is where circle in and θ is the central O radians. r i r 2 Similarly , The area area of the of the formula a sector for the with a area central of a circle angle θ is: will area be a = πr fraction of the circle. ➔ Area of sector = where r is the radius of the circle and θ is the central angle, in radians. Example a Find a the length central angle of of the 2.6 arc which radians subtends (see diagram) i in b a circle Find the of radius area of 7 the Arc length = 7(2.6) = 18.2 cm Arc length = rθ 2 2.6 (7 2 ) r 2 b Sector area = = 2 Trigonometry 2.6 radians 7 cm sector. Answers a = cm. 63.7 cm Sector area = 2 The abbreviation for radians is rad. In the example above, Another 2.6 radians could be written as 2.6 rad. If you see an angle angles no units, such as ‘sin 2.6’, you can assume that the angle way of writing with is 2.6 radians. in radians c is 2.6 stands where for the c circular measure. Example A circle has subtended radius by an 2.5 mm. arc of Find length the size of the central angle 9 mm. Answer 9 = 2.5θ Arc length = rθ 9 2.5 3.6 rad Example In this circle, arc AB = 7.86 cm and the area of Some sector 2 AOB = 23.58 cm . Find the central angle θ and the radius their r A farmers crops patterns. real-life are in plant circular What other applications there for circles, i B arcs r O and sectors? Answer 2 2 r r 2 23.58 = , so 47.16 = θr Sector area = 2 2 7.86 7.86 rθ, = Arc = so length = rθ r 7.86 2 47.16 = (r ) = 7.86r, so Substitute for θ in the previous r equation. 47 r 16 = 7 = 86 6 cm 7.86 7.86 , = so θ = 1.31 rad Use the = result r 6 Exercise 1 Find of 2 1.7 Find of the K length radians the 3.25 of in length radians the a of at arc circle the the which with arc radius which center subtends of a a central angle 5.6 cm. subtends circle an with angle diameter 24 cm. Chapter An 3 of An 4 is circle. arc a circle of sector arc circle In at the by value an radius an θ of angle arc if of 50 cm. of the 2.4 Find length circle radians the 12.5 mm has area at at radius the and the center 2.5 mm. center O perimeter AOB WX with the the subtends with subtends radius EXAM-STYLE 6 subtended Find AB of An 5 θ angle a 3 an cm. angle Find of 5.1 the radians area and at the center P perimeter of of a sector WPX QUESTION circle with center. If center the P the length of arc arc QR QR subtends is 27.2 an cm angle and the of θ area of 2 7 sector PQR Circle O The has centers intersect the is at 217.6 radius of A the and cm , find 4 cm, and circles B, find are the θ and circle 8 cm blue the P radius has apar t. shaded of radius If the area the 6 circle. A cm. circles O in b P a diagram. B Degrees Y ou have and radians already seen that one full rotation around a circle gives a Any central to angle 360°. Y ou 2π, of can and use you this know fact to that one convert full rotation between is radians also and angle which equal degrees. is a multiple is assumed measured 360° = 2π, = 1 so 180° = of to in π be radians π. so you don’t need to 180 and radian write ‘rad’. 1 radians = 180 ➔ To conver t degrees to radians multiply by ➔ To conver t radians to degrees multiply by Example Exact a Conver t these angles to radians: 30°, 45°, are Give exact Conver t these angles to degrees: rad, 5 Give exact Trigonometry written multiples rad 9 answers. { values as answers. 2 b radian 60° Continued on next page of π Answers 30° a 180 180 180 2 180 180 180 5 9 these values Conver t Give 20° Conver t Give Multiply by = b 72° 180 = Example 3 180 = 9 a = = = 5 4 60 60 2 = b 180 = by 6 45 = Multiply 180 60° = 45 = = 45° 30 = 30 angles to these values 3 to significant angles to radians: one to 43°, 136° figures. degrees: decimal 70°, 1 rad, 2.3 rad place. Answers 43° a = = = = 1 rad rad (3 sf) = 2.37 rad (3 sf) 180 180 = 1 180 = 1.22 = b sf) 136 136 (3 180 = = 180 rad 70 0.750 180 70 136° = 180 70° 43 43 57.3° (1 dp) 180 2.3 rad = 2.3 = Exercise 1 Conver t Give a 2 a 3 these 75° Give b these 56° Give b these exact angles 240° angles to 3 radians. c to angles c to 80° d 330° d 230° radians. significant 107° figures. 324° degrees. b to values. a dp) values. answers Conver t (1 L exact Conver t 131.8° c d Chapter Conver t 4 Give 1.5 a In Section often radians. 11.1, you in to degrees. significant 0.36 45°, used is 3 b 30°, It angles to rad triangles: are these answers rad looked 60° and to 2.38 c at some 90°. trigonometr y helpful figures. remember angles angles, they these 3.59 d ‘special’ These and rad can and also angles, right-angled their be so in rad multiples, expressed you do not T o in have to change mode choose do the conversion ever y time. The table shows some special degrees and their equivalents in radians as multiples of radian and 5:Settings & angles Status in to press | 2:Settings | π 1:General Angle in Use 30° 45° 60° 90° 120° 135° 150° 180° 210° the degrees move to select Angle in 3 2 to Angle and Radian. 5 7 5 key 225° Press and then π radians 4 6 3 2 3 4 6 6 4 select to Angles which are multiples of 30°, 45°, 60° and 90° are 4:Current return to the usually document written When in you whether To exact find solve the set Example are cosine your form using trigonometr y angles sine, radians, radian given and GDC problems in degrees tangent to π radian values you or must be careful to note radians. for angles measured in mode GDC help on CD: demonstrations Plus The diagram shows a circle O and radius 5 GDCs cm. 5 cm Find to 3 the area of significant the shaded region, O figures. 1.46 rad D Answer 2 (1.46 ) Area of sector OCD (5 ) = Area of the shaded region = area 2 2 = 18.25 sector OCD – area cm 1 Area of OCD Area = ab 2 1 (5) (5) = sin (1.46 ) 2 ≈ 12.42335... Shaded area 1 = 18.25 (5) (5) – 2 2 ≈ 5.83 cm Trigonometry (3 sf) sin Casio the (1.46 ) sin C of OCD of are on TI-84 FX-9860GII with C center and Alternative for the CD. Exercise 1 Find M the exact value of Find c tan d the value of each ratio. cos b 2 trigonometric sin a each sin trigonometric ratio, to 3 significant figures. cos a 0.47 EXAM-STYLE 3 The = 1.3 A 4 The c tan 2.3 d cos 0.84 shows the circle, center A, radius 4.5 cm, and radians. C 1.3 1.25 QUESTIONS diagram BÂC sin b a Find the area of b Find the length c Find the area ABC BC rad 4.5 of the shaded region. B diagram shows the circle, center O, A with 11 m 3 m radius 3 m, AB = 11 and AÔB = 0.94 radians. 0.94 Find the shaded B area. O 5 The 6 diagram cm, QR = shows 11.2 the cm P circle, and PÔQ center O, = 1.25 with radius radians. a Find the area of POQ b Find the area of QOR c Find θ d Find the 6 cm Q 1.25 i (PÔR). M O 11.2 cm length of arc PMR R Review exercise ✗ 1 In triangle Find 2 In a the length triangle Find ABC, of XYZ, ˆ X ZY.  = ˆ B = 45°. The length of AC is 7 cm. AB XY = b 8 cm, Find XZ = 16 cm, and ˆ XY Z = 90°. YZ Chapter EXAM-STYLE 3 A straight point with with the Find QUESTIONS line passes through coordinates (5, 2). the origin The line (0, 0) forms and an through acute the angle of θ x-axis. the value tan θ of Z 4 cm 4 The diagram shows triangle XYZ, with XZ = 4 cm, XY = 10 cm, 30° ˆ X and = 30° X Find the area of triangle 10 cm Y XYZ B A 5 The diagram AÔC = 2.5 Find a shows a circle, center O and radius 10 cm. 2.5 radians. the length of arc C ABC 10 cm O Find b the Review 1 An the How top tall of the shaded sector. exercise obser ver sees area is standing of the the 100 m building from at an the base angle of of a building elevation of 36°. building? y 2 The diagram shows par t of a unit circle (radius 1 unit) C D with center a Angle b Point Find O AOB C = has angle 32°. Write coordinates down the (0.294, coordinates of B B 0.956). E AOC A x 0 c Angle COD EXAM-STYLE = 54°. Find the coordinates of D QUESTIONS ˆ 3 The diagram shows triangle XYZ, with X= Y 42.4°, 13.2 cm ˆ Z = 82.9° and XY = 13.2 cm. X 42.4° a Find ˆ Y b Find XZ 82.9° Z 4 The diagram shows triangle PQR, with ˆ Q = 118°, PQ = 9.5 m P 9.5 m and QR = 11.5 m. Q a Find PR b Find ˆ P 118° 11.5 m R Trigonometry 2 5 This diagram a Find ˆ ACB, b Find AB shows the given triangle ABC, that it is an which obtuse has an area of 10 B cm angle. 5.83 cm A 6 Two ships Ship A sail from the same por t P at the same C 4 N time. A sails on a bearing of 050° for a distance of 24 km before 24 km droping anchor. 50° Ship B sails on a bearing of 170° for a distance of 38 km before P droping Find 170° anchor. the distance between the two ships when they are stationar y . 38 km B 7 The diagram shows quadrilateral ABCD, with AB = 7 B cm, 9 cm BC = 9 cm, CD = 8 cm, and AD = 15 cm. Angle ACD = 82°, 7 cm C y° angle CAD = x°, and angle ABC = y° A a Find the value of x. b Find AC c Find the value of y. d Find the 82° x° 8 cm area of triangle ABC 15 cm D 8 The diagram Angle DAC shows = 0.93 a circle radians, a Find BC b Find DB c Find the length d Find the perimeter with and center A angle and BCA = radius 1.75 12 cm. B radians. D E of arc DEC 1.75 of the region BDEC 0.93 12 cm A C Chapter CHAPTER 11 SUMMARY Right-angled For any triangle right-angled triangle opposite ● sine θ an angle θ: adjacent O = = ; hypotenuse cosine θ A = = ; hypotenuse H opposite tangent θ with trigonometry H O = = adjacent A H O ● i A ● The trigonometric ratios of ‘special angles’ are: angle 30° sine cosine tangent 2 √3 measure 1 3 1 3 60° = ° 2 2 3 3 1 1 2 1 1 2 1 = ° 2 2 1 2 2 1 = 1 = 45° 3 3 1 = ° 2 2 Applications of 45° 3 1 right-angled triangle trigonometry angle of elevation horizontal ● The angle of elevation is The angle of depression The four east (E), the angle ‘up’ from horizontal. angle ● cardinal and compass west Three-figure is the angle points ‘down’ are nor th from (N), south depression (S), (W). bearings of horizontal. N give directions as clockwise from nor th. 40° Using the coordinate axes in trigonometry O40° ● For ● For ● For ● These supplementar y any any three sin sin θ θ°, angle = sin θ proper ties 2 1 θ, angle angles α and sin (180°– = β, θ), sin (180°– are tr ue sin α for and θ), = cos θ and any sin β, = and cos α = – cos (180°– cos θ = = N40°E –cos β θ) –cos (180°– θ) angle θ: 2 θ + cos θ = 1. sin 2 tan = cos y 3 For any line y = mx which forms an angle of θ = mx with i the x-axis, the value of m (the gradient of the line) is tan θ x Continued Trigonometry on next page The ● sine For any rule ABC, B a is the length of the b is the length of the c the c side opposite Â, side opposite ˆ B , opposite ˆ C, side and is length A sin B There the b can sine = A sin B sin C c be r ule c = or = sin ● b C b sin C = a the A a sin of a an ambiguous case when you use if: B ○ you are given two sides and a non-included B 5 3 acute ○ the angle side 5 32° opposite the given acute angle is A the 3 32° b C A shor ter The ● of cosine The cosine 2 a = b = a + c + c + b 2 A C states that: – 2bc cos A B – 2ac cos B – 2ab cos C or c a or 2 a 2 b cos b sides. 2 2 = given 2 2 2 c two rule r ule 2 2 b ● the A C b 2 + c − a = 2bc 2 2 a cos B 2 + c − b = 2ac 2 2 a cos C 2 + b − c = 2ab Area ● The of a area triangle of any triangle ABC 1 area sin A or area = 2 Radians, For ● a sector Arc by the formula: 1 ac sin B or area with of and central sector 2 sectors angle = ab sin C = 2 arcs length given 1 bc = is θ radians in a circle of radius r : rθ ● Area of sector = ● To conver t degrees to radians, multiply by ● To conver t radians to degrees, multiply by Chapter Theory of knowledge Units of measurement Mathematics However, is this often considered language actually a ‘universal has many language’. forms. There Angles can be measured in different units: degrees are number radians. Why do we need more than one unit other or systems as of well as the decimal measurement? (base-10) Actually , different we don’t forms of need different measurement units have of measurement. developed in But which we different Another par ts of the world and at different times. system which The idea of thousands of sexagesimal to the to 360 The fact 360° years a that the full to (base-60) the circle ancient number orbit is of thought date Babylonians, system. the to Ear th It may about the is is around be Sun used a binar y related is Where the The 322 tablet 1800 script numbers numbers arranged and in show triples dates BCE. from Scholars – into are moder n Old have written in digits, base are columns Pythagorean the Babylonians these more years before were than the using 1000 time of Pythagoras. What is a Pythagorean Why is called Theory of 2. is the system commonly close Babylonian translated the What this triple? tablet Plimpton knowledge: Units 322? of measurement and 60. discovered that do measure base cuneiform all binar y, base back who also impor tant used? days. Plimpton times, in system use. we in 60? The radian more sensible related type unit of to the angle of unit in 1870s. How are angles, measurement the Today , geometr y , for measurements mathematicians, the measurement term radian in a had circle. been related to be are a much closely Although used wasn’t measurement and to radians ‘radian’ trigonometr y radians as seems previously much is this by used until commonly used calculus. the measurements in a circle? Who measures angles in gradians? [ Angles are not the only area in which different units The was measurement A look that at the the are units ‘universal universal as we common. of might like to of distance and mass mathematics’ may radian used papers currency, language term of will not by show be in written James Thomson in the early in Belfast. 1870s as think. D EE SP IT M LI driver that the speed limit is 30, but give no units. 30 Which speed is actually faster? 30 Would rather you be a millionaire in the UK US, or China? 6000 Which kg 7 elephant is (US) 11 000 pounds heaviest? Do to tons you be think truly What sor t been sent it is possible for any language ‘universal’? of mathematical into communicate deep with information space, other to has perhaps intelligent life- forms? Chapter Vectors CHAPTER Vectors 4.1 of a zero OBJECTIVES: as vector ; vector , vectors; The 4.2 scalar Vector column the base between 4.3 displacements the plane representation vector vectors product in –v; i, of j the and sum multiplication and two k; by position vectors; in three and a dimensions; difference scalar ; of components two magnitude vectors; of a the vector ; unit vectors. perpendicular vectors; parallel vectors. Angle vectors. equation of a line in two and three dimensions. The angle between two lines. Coincident 4.4 whether Before Y ou 1 two parallel lines you should Use and lines. Point of intersection know in OABCDEFG is A lies on D the y-axis and lies down the A coordinates lines. Determining start coordinates units. two intersect. how three to: Skills dimensions. 1 e.g. of a cube x-axis, on the coordinates with C lies z-axis. of A, sides B on 2 has the 2 Write and The check cuboid, length units. y-axis A 3 OABCDEFG units, lies and D on on F OC the the 4 is such units x-axis, C that and on OA OD the z-axis. Give the coordinates of G has (2, 0, 0). G B has coordinates C (2, 2, 0). D D F has coordinates F A b B c E d F e H, F 4 the midpoint 2 C (2, 2, 2). a GF B O E 3 E O B A A 2 Use e.g. of a Pythagoras’ Find the triangle theorem. length with of the other 2 Find the length of the hypotenuse, x, sides 4 cm, 7 cm. x 3 2 x x 2 = = 7 2 + 65 Vectors 4 = = 65 8.06 cm 6 hypotenuse, x of 3 Use e.g. QR the In = cosine triangle 11 cm Calculate 2 PR = PQ = PQ = a triangle BC 6 cm, = correct PR ABC, 15 cm Calculate 95°. of In to AB and the the = angle length 9 cm, ABC of nearest = 110°. AC cm. 2 + QR – 2PQ × QR × cos 95° b In triangle ABC, AB = 8.6 cm, AC = 9.7cm. 2 = 6 = 145.49. = ˆ Q length 2 2 PR PQR, and the 3 r ule. + 11 12.1 cm – . 2 × . (3 6 × 11 × cos 95° BC = 3.1cm Diagram sf) and B NOT accurately 3.1 cm drawn 8.6 cm C 9.7 cm A Calculate angle ABC to the nearest degree. Chapter Some quantities require one can piece temperature is be of described information. 37 °C, the length by a For of single number example, the – normal Amazon river is they only body 6400 km, the –3 density of water magnitude However, direction vectors. you I They some to you are are alone and quantities wish what used used is are fly represent not them. 340 km, direction a only Such from this you in quantities are determined by called scalars yourself extensively to These require define to distance you . 1000 kg m completely the tell Vectors (size) If that until is of to branch quantities quantities London piece need magnitude as also called Paris and is I tell useless in! Physics such are information travel of to but called Mechanics. displacement, force, Y ou weight, velocity interested in velocities. The questions and vectors final where the then leads Vectors basic on as and will the Mathematics be of this able to of see vocabular y basic operations has these and a are and of applications in notation This of geometr y both chapter vectors of may wish to primarily number problems. and we displacements chapter three-dimensional concepts, to In representations exercise you two-dimensional with momentum. deals and vectors. explore the vectors in role of Mechanics. . If you have A Vectors: travel you basic ki lometres concepts north and ki lometres east, how far traveled? simple question perhaps – but a question with two sensible answers: ● One answer to this question is to say that you have 3 km traveled F inish 7 kilometres. through (4 This + 3 = is 7 the total distance that you have moved kilometres). 4 km Start ● A second answer to this question is to say that you have 3 km traveled F inish 5 kilometres. This 2 theorem ( value has been found using Pythagoras’ 2 4 = + 3 5 kilometres). This value is called the 4 km displacement . position and It measures your final the difference between your 5 km initial position. Start Vectors ➔ A and is vector direction. ➔ A of As can have scalars be velocity and something the For at rate is traveling if This of hour and is whereas think per size (magnitude) are displacement size a and no direction. velocity . Examples displacement also to tr ue how velocity changes car then but and speed. refers something we has and distance Speed has vectors that distance meanings. which that of quantity above, kilometres is fast refers its that this of is to position. traveling the speed. that car star ting place, the was line then star ting If a speed. instance, 90 car’s If at quantity are seen different a Examples is scalar scalars same direction, and its line the would car per be was one hour around finish velocity after kilometres traveling line when it a track were in retur ns where the to the same the zero. traveling hour we down would a straight say that road its in a velocity westerly is 90 west. Chapter Representation Vectors of the on are line the Consider represented represents line of (indicted the points vectors using the by size an directed of the arrow) A(2, 3) and line segments vector shows B(5, 7) quantity the on where and direction the the the of Car tesian length direction the vector. plane: y 8 B 6 4 A 2 0 x 2 To in 3 describe the is (or positive the y) the the called x direction the describe from and horizontal component . movement This movement are The 4 4 A B units (or we in could the of impor tant. this We say the movement can ‘move positive y x) component, direction both to 6 4 units direction’. is and therefore 3 the vertical the use a The length vector of to this. vector can be represented in a variety of ways: In In the diagram the line AB represents the vector AB where a column ⎛ x ⎞ the vector arrow over the letters indicates the direction of the movement to B). The components of the vector are here represented , ⎟ y ⎝ x A ⎜ (from represents vector a using movement column the ⎠ in the form. positive x and y direction 3 AB = 4 in Vectors For can the a movement also example we be represented could use a to using a lower represent the case bold vector AB letter. the positive y direction. . 3 a = AB = 4 B Bold letters difcult hand to so are write by instead when a 4 writing you underline to show should the that letter it is vector . A 3 So a hand Vectors is written as a by a Finally the vector can be represented in uni t vector form . We can 3 write as 4 3i + 4j where i and j are vectors of length 1 unit in the j directions of x and y respectively . i and j are called base vectors. i The vector positive As x well 3i + 4j therefore direction as objects and that 4 means in the move a movement positive along a flat y of 3 units in the direction. surface in two dimensions, k also think space. way about We as can above objects that represent but we a move vector introduce around in the three in dimensions letter k j three-dimensional for the in vector a similar of length i one So unit now in the we z-direction. have three components. 3 2 = 3i − 2j + k would therefore represent a movement of 3 units 1 in the unit ➔ positive in the The x-direction, positive unit 2 units in the negative y-direction and 1 z-direction. vector in the direction of the x-axis is i. ⎛ 1 ⎞ ⎛ 1 ⎞ In two dimensions i = ⎜ and ⎜ ⎝ in three dimensions ⎟ 0 i ⎟ 0 = ⎜ ⎠ ⎟ ⎜ ⎟ 0 ⎝ ➔ The unit vector in the direction of the y-axis is j. In ⎠ two ⎛ 0 ⎞ ⎛ 0 ⎞ dimensions j = ⎜ and ⎜ ⎝ in three dimensions j = ⎟ 1 ⎠ In three z-axis dimensions ⎟ ⎜ ⎝ ➔ ⎟ 1 ⎜ the unit vector in the ⎟ 0 ⎠ direction of the is ⎛ 0 ⎞ ⎜ k ⎟ 0 = ⎜ ⎟ ⎜ ⎟ 1 ⎝ The ⎠ vectors Example Write a = k are called base vectors 6 ⎞ ⎜ ⎟ ⎜ ⎝ b j, ⎛ a i, Write i + in unit vector form. ⎟ 7 5k ⎠ in column vector form. Answers a a = 6i ⎛ 7j 1⎞ ⎜ b b = ⎟ Here 0 ⎜ ⎟ ⎜ ⎟ ⎝ 5 the coefficient component is of the j zero. ⎠ Chapter The The magnitude magni tude of AB of a is vector the length of the B vector Other and is denoted by |AB names magnitude Magnitude is found for |. by using Pythagoras’ are theorem. modulus, a length, norm 4 ⎛ 3 ⎞ and 2 AB If = ⎜ ⎝ then ⎟ 4 |AB | = size. 2 + 4 3 = = 25 5 ⎠ A 3 a 2 ➔ AB If = In three = b ai + bj then |AB |= a 2 + b dimensions this becomes a b ➔ AB If = 2 = ai + bj + c k then |AB | a = 2 + b 2 + c c Example When Find the magnitude of these 5 ⎞ ⎛ a OP = ⎜ problems ‘uniform deal of acceleration’ ⎟ ⎜ 2 b ⎟ with vectors 3 ⎞ ⎛ physicists and ‘free fall under ⎟ ⎜ 12 ⎟ ⎜ 1 ⎝ gravity’ to consider magnitude 2 ( −5) |OP |= 2 + 12 need ⎠ Answers a they direction = 169 = the and of the 13 acceleration ⎛ 3 ⎜ ⎟ b ( −2 ) 14 = = 3.74 ⎠ fur ther . A unit vector form. ⎛ ⎛ x = ⎜ b ⎝ y = ⎟ 3 1⎞ ⎛ 0 ⎞ 2 ⎞ ⎜ ⎜ ⎝ ⎠ c ⎟ 7 z ⎟ 1 = ⎜ ⎟ ⎠ ⎜ ⎟ 1 ⎝ 2 Write a AB Vectors these = 2i in + column 3j wish to (3 sf) ⎟ 1 Write these in a may 2 + 1 explore Exercise 1 + ⎟ ⎜ ⎝ 3 Y ou 2 2 = 2 ⎜ vector . ⎞ b vector CD = ⎠ form. −i + 6j − k c EF = k this concept Write 3 the vector vectors form and a, b, c, column d and e vector in the diagram in both unit form. a c d e b Find 4 the magnitude ⎛ 1⎞ ⎜ ⎟ ⎝ 3 a b 4 Find 5 the 3 Equal, ➔ vector. 2.8 2i + 5j d ⎠ of each 2i c + 2j + k 2 d e 3 Two vectors are j − k 6 negative − 5j 3 1 2i b e 4.5 vector. 4 5 each c magnitude 2 a 3 of and parallel if equal they vectors have the same direction and the It does where same magnitude; their i, j, k components are equal too, and column vectors are the Car tesian these vectors equal. are Consider matter the so plane their not in following: – they are still equal. B Vectors AB and PQ are pointing in the same Q direction (are parallel) and have the same If magnitude. Therefore AB = two equal PQ vectors in are length then A their be P components the will same. ⎛ Here The two vectors AB and MN have the same = AB PQ = ⎝ magnitude So AB ≠ but MN different directions. 2 ⎜ B ⎞ ⎟ 5 ⎠ M . A N ⎛ 2 ⎞ Here AB = ⎜ ⎝ ⎟ 5 ⎛ and MN = 2 ⎞ ⎜ ⎝ ⎠ ⎟ 5 and so AB = –MN . The direction vector MN ➔ is called Y ou can the negative write AB as vector – of a ⎠ not is just impor tant, its length. BA Chapter D Vectors AB , CD EF and are all parallel but B ⎛ AB have different = 2 ⎜ magnitudes. ⎝ ⎞ = ⎟ 5 2i + 5j ⎠ 1 AB Here CD = AB and = 2EF 4 ⎛ CD 2 = ⎜ F ⎝ ⎞ = ⎟ 10 4i + 10j ⎠ A ⎛ EF = ⎝ ⎞ ⎟ 2.5 = 1i + 2.5j ⎠ E 1 AB Here 1 ⎜ CD = and AB = 2EF C 2 ➔ Two So, vectors AB and quantity . AB Vectors are RS This and parallel are can if one parallel also be if is a AB written scalar = k RS as a = multiple where k of is the a other. scalar kb GH B ⎛ of 29 but different directions. So AB ≠ GH AB = ⎝ ⎛ H GH = We ⎞ ⎟ 5 5 ⎜ ⎝ A 2 ⎜ 2i + 5j ⎞ ⎟ 2 = ⎠ = –5i + 2j ⎠ cannot multiply AB G by Example The diagram shows several vectors. a c e d b Write each of the other vectors in terms of the vector a Answer From the diagram we can see the following: a = ⎛ 3 ⎞ ⎜ ⎟ 5 ⎝ ⎛ 1.5 ⎞ , b = ⎝ ⎠ ⎛ 3 ⎞ d = ⎜ ⎝ ⎟ 5 ⎠ ⎛ , ⎜ e = ⎟ 2.5 6 ⎜ ⎝ c = 6 ⎜ ⎝ ⎠ ⎞ ⎟ 10 , ⎠ ⎞ ⎟ 10 ⎛ , , ⎠ { Vectors Continued on next page a scalar to get GH therefore 1 b = – b a is parallel a, to in the opposite 2 direction c = c –2a is in twice d = d –a is = e 2a is the in with e For m what = 3i + half opposite the magnitude direction to a, with magnitude the the in twice Example with the opposite same the the direction to a, magnitude same direction as a, with magnitude values t j – of 6k t and and n s = are 9i – these 12j + two vectors parallel? s k Answer For parallel vectors 3i + t j – 6k = k 3i + t j – 6k = 9ki (9i 3 = m – – = kn 12j + sk) Multiply 12k j + skk From i components From j components From k out and equate coefficients. 9k 1 k = 3 1 So t = –12 = × –4 3 1 –6 = s × ⇒ s = –18 components 3 Exercise 1 The B diagram shows several vectors. c a f e b d a Write the b 2 vector How Which ⎛ 0 a = 0 = g = –i a the or and vectors 7 c, d, e and f in terms of b b related? vectors b are parallel ⎛ 1⎞ = ⎜ ⎟ 1⎞ ⎝ ⎠ 7 to i + 7j? ⎛ c ⎠ 0 05 ⎞ 0 03 = ⎜ ⎝ ⎟ ⎠ 10 ⎞ ⎜ ⎝ a of these ⎟ ⎛ d are of ⎜ ⎝ each ⎟ 70 + e = 60i + 420 j f = 6i – 42j ⎠ 7j Chapter For 3 what a r = b a 4i value + t ⎛ = For v 5 = 8 t i In the of each and are s = b = 5j + of t 8k – two vectors parallel? 12j 7 ⎞ ⎟ 10 ⎝ values cube 14i ⎜ ⎠ – these ⎛ and ⎟ what t ⎞ ⎜ ⎝ 4 t j of and and ⎠ s w OABCDEFG are = the these 5i + j two + vectors parallel? s k length G edge is one unit. D Express these vectors in terms of i, j and k OG a E O B 6 b BD c AD d OM A where M Repeat question OA units, = 5 Position is 5 OC the midpoint given = 4 that units of GF OABCDEFG and OD = 3 is a cuboid where units. vectors y Posi tion are vectors vectors giving the position 15 of a point, relative to a fixed origin, O P(–5, 12) The point P with coordinates (–5, 12) has 10 5 ⎞ ⎛ position OP vector = ⎜ ⎝ = ⎟ 12 −5i + 12j ⎠ 5 x –6 ➔ The OP point = ⎛ x ⎞ ⎜ ⎟ ⎝ y P = The x i + coordinates (x, y) has position –2 0 vector y j ⎠ Resultant Consider with –4 vectors the points A(2, 3) diagram shows the and B(6, 6). position vectors of A and B. ⎛ 4 ⎞ We can see that the vector AB 8 = ⎜ ⎝ ⎟ 3 B ⎠ 6 Remember We can also see that to move from A to B that AB we 4 should A could describe this movement as either from A to B or first going from A to a vector , not then Vectors from O to B as O coordinate and written as going 2 directly be O 2 4 6 8 pair . a Thus The we vector Recall and could AB is called AO = – OA, AB = – OA that AO = the + OB. resultant of the vectors AO and OB. hence = ➔ AB write To find we can vector Find A the OB OA vector position AB between vector of A two from points the A and B position B and the – resultant subtract of Example Points the OB + B have vector coordinates (–3, 2, 0) and (–4, 7, 5). AB Answer A(–3, 2, 0) B(–4, 7, 5) O First we write ⎛ ⎜ OA down the position vectors OA and OB. 3 ⎞ ⎟ 2 = ⎜ ⎟ ⎜ ⎟ 0 ⎝ ⎠ ⎛ 4 ⎞ ⎜ OB = ⎟ 7 ⎜ ⎟ ⎜ ⎟ 5 ⎝ AB = ⎠ OB – OA = ⎛ 4 ⎞ ⎛ 3 ⎞ ⎛ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ 7 ⎜ ⎜ 2 5 ⎝ Similarly vector are if PR given we know then each relative to a the point ⎟ 5 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ 0 vector of = 1⎞ ⎟ ⎟ 5 PQ points ⎠ and Q the and Q R P. R Now P QR = QP + = PR – PR PQ Chapter Example 2 ⎞ ⎛ 0 ⎞ ⎛ ⎜ Given that = XY ⎟ ⎜ 1 ⎜ ⎟ ⎜ ⎟ XZ and ⎟ = 10 ⎜ ⎟ ⎜ 3 ⎝ ⎟ ⎠ 1 ⎝ Find the vectors YZ a ⎠ ZY b Answers a YZ XZ = XY − ⎛ 0 ⎞ ⎛ 2 ⎞ ⎛ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ = 10 1 ⎜ ⎜ 1 ⎝ b ZY ⎛ 2 ⎞ ⎛ ⎜ ⎟ ⎜ = −11 ⎜ ⎜ Exercise 1 P has Find ⎟ = 11 ⎟ ⎜ ⎟ ⎜ ⎟ ⎟ 3 ⎠ ⎝ 2 ⎠ ⎝ ⎠ 2 ⎞ ⎟ = 11 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ ⎟ ⎟ 2 ⎝ 2 ⎞ 2 ⎠ C coordinates the vectors (7, PQ 4), Q has coordinates (2, 3). QP . and 5 2 Point A has position vector C has position 1 3 4 Write these vectors . bj + c k c the vector from (2, –3, 5) to (1, 2, –1) d the vector from (1, 2, –1) to (2, –3, 5) ⎛ 1⎞ ⎜ ⎟ LN ⎟ AB TS ⎛ 1⎞ ⎜ ⎟ y , = . ⎟ ⎜ ⎟ BC 3i origin Find LM ⎠ + 4j − k and TU = 2x 3 = and AC i − 1 4j 4 = . ⎜ ⎟ ⎜ ⎟ ⎠ z 2 the Vectors the 3 that ⎝ Find to ⎟ ⎜ ⎝ ⎠ = CB 4 ⎞ 2 NM 0 Given (1, –5, 6) ⎜ ⎟ vectors: (2, –3, 5) ⎛ and 2 ⎠ form. joining ⎝ + column d vector is as AC c ai these the ⎜ 6 Write b P ⎟ 3 ⎝ OP where vector ⎜ a ⎜ 5 in position ⎠ BA b has ⎟ 4 ⎝ AB B vector ⎜ a 1⎞ ⎛ , 2 ⎞ ⎛ and values of the x constants x, y and y z + 2k, find US. The following example demonstrates how to show that three points Collinear are points all lie collinear in Example Show 2i + a straight line. that the 3j k points and A, 4i B 7j + and 7k C with position respectively are vectors i 2j + 3k, collinear. Answer Star t AB OB = + = OA − (3 −3i ( + 2))j 5j + ( 1 any 3)k = (4 = 3i AB OC = 1)i 5j 2i + lie The that 3j + points points, for example, using any two other (7 points, 3)k for AC example A, on = scalar a points the BC parallel that A, same B AC, line. we 6i could 10j multiple showing both parallel + of 8k found which both that to have AB is AB and a and AC are BC. points and 4i A, 7j B + and 7k C with position respectively are vectors i 2j + 3k, collinear. QUESTION A, B and C have coordinates (2, 3, –3), (5, 1, 5) and respectively . AB a Find b Show Show are contain the k (8, –1, 13) 3 the D EXAM-STYLE 2 2))j AC point must Show of repeat Note they C joining 4k since Exercise 1 ( and common and 7 AB Hence vector AB 4k AC = and, ( + the OA − + finding two Now AC by (−2−1)i that that A, the B and points C P are collinear. (1, 2, 4), P 1 (–2, 1, 4) and P 2 (–5, 0, 4) are 3 collinear. Given that is P also collinear with 4 x-coordinate P , P 1 of is P 2, find the y and and 2 P and the 3 z-coordinates. 4 4 The position vectors of respectively . Find the and ratio AB find the A, B value : and of x C so are given that A, B by 3i and C + 4j, are xi, i − 2j collinear BC Chapter Distance ➔ If A = between (x , y 1 , z 1 ) two then a points OA = = x 1 in i + space y 1 j + z 1 k 1 A and if B = (x , y 2 , z 2 ) b = OB then = x 2 i + y 2 j + z 2 k 2 b AB AO = – a OB + a B = OB = b = (x − OA − b a O − x 2 )i + (y 1 − y 2 )j + (z 1 − z 2 )k 1 2 Distance Example Find the distance AB (x = x 2 2 ) ( y 1 y 2 ) 2 (z 1 z 2 ) 1 vector from between A(1, 3, 4) the two to B(4, 2, 7) and hence determine the points. Answer OA = AB = i + 3j OB − + 4k First OB and = 4i + 2j + write position = (4i = 3i + j = 2j + + |AB Exercise 1 Find the A | 7k) (3 ) vector the EXAM-STYLE Point vectors. (i + 3j + 4k) 2 + ( −1) 19 = = 2 + (3) 4.36 (3 sf) E determine 2 AB from distance A(–1, 5, 1) between QUESTION has position the ⎛ 5 ⎞ ⎜ ⎟ 2 vector ⎜ ⎜ to B(4, 5, –1) two and hence points. 6 , B has position ⎟ ⎜ position vector and 6 ⎠ 8 ⎞ ⎛ has 0 vector ⎟ 4 ⎝ C as 3k 9 + 1 + 9 = points OA 2 Distance the 7k ⎟ 10 ⎜ ⎟ ⎜ ⎟ 1 ⎝ 3 Show that If position the find two Given Vectors that ABC vector possible EXAM-STYLE 4 triangle ⎠ a is of values isosceles, a of point and calculate (2, –3, t) is such the that angle CAB |a|= 7, t QUESTION a = xi + 6j − 2k and |a| = 3x, find two possible values of x a a u = 5 , 2 4 v = 2a a 6 and Find Given b are the two value vectors of |a + b = 2a c b is per pendicular b b is vector find the |u| = |v|, find the possible values of a and b| = to |a| = 5. when −3a a and |b| = 12 vectors uni t To that a Unit A . 2 a unit length of a vector vector the in of the vector a, length same 1 in a given direction namely |a|, as and direction. a vector a then first multiply find the 1 vector since a it . by is a This scalar vector will multiple of be a in and the same will be direction one unit long since it 1 is × ➔ A the length vector of of the length original 1 in the vector. direction of a is found by using the formula Using length and ➔ this k, in then A method the formula Example a Find can direction multiple vector we of this of by length also k a. find We a vector would of first any find length, the unit say vector k. in the direction of a is found by using the k the unit vector in the same direction as the vector 3i + 4j 3 b Find a vector of length 10 in the same direction as ) ( 1 Answers 2 a The vector 3i + 4j has length 3 2 + 4 = 25 = 5 1 Therefore a vector of length 1 will be 3 (3i + 4 j) = 5 ⎛ b The vector 3 ⎜ ⎝ 1 has length 10 . The vector ⎠ the vector of length 10 is This 10 can 3 10 1 be simplified 10 10 = 3 10 10 if 3 ⎞ ⎝ ⎟ 1 has length 1. ⎠ 3 ⎞ ⎟ 1 required: 1 ⎛ ⎜ 10 ⎛ j 5 ⎜ 10 10 Therefore 5 ⎞ ⎟ 1 4 i + = 10 3 1 Chapter Exercise F 3 1 Show that 4 i 5 1 2 Show that 2 i 3 3 Find a unit is j a unit vector. 5 2 j 3 k is a unit vector. 3 vector parallel to 4i – 3j ⎛ 1⎞ ⎜ 4 Find a unit vector parallel to the vector ⎟ 5 ⎜ ⎟ ⎜ ⎟ 4 ⎝ 5 Find a unit vector in the direction of the ⎠ vector between the Show points P (1, 0, 1) and P 1 that magnitude 6 ai + 2aj is 7 Find a 1 unit vector EXAM-STYLE of long. Given magnitude that 5 a that > is 0, find the parallel to value 2i ⎛ QUESTION – Find a vector of magnitude 7 in the direction of of a j −1 ⎞ ⎜ 8 ⎟ −3 ⎜ ⎟ ⎜ ⎟ 2 ⎝ 9 Find a unit vector in the b 2 sin Addition Addition of direction as 1 and tan subtraction of we vectors vectors ⎛ 3 ⎞ ⎛ 5 ⎞ Suppose have two vectors u = ⎜ ⎝ ⎟ 0 and v = ⎜ ⎝ ⎠ ⎟ 4 ⎠ u v Now u + v along is vector Vectors inter preted u’ followed ⎠ . same 2 cos a the (3, 2, 0). 2 geometrically by ‘move as along first ‘move vector v’. is 1. ➔ The resultant formed head when to u vector, u and u + v v, are is the placed third next side to of each the triangle other tail. + v v u Notice also that vector addition is commutative The since u + v = v + u. This gives rise to the word ‘commute’ exchange of vector means to parallelogram or switch. addition. In mathematics, the commutative u proper ty u + order means without you can affecting switch the the outcome. v By ⎛ 8 ⎞ The considering calculations, u resultant vector u + v in this case is ⎜ ⎝ ⎟ 4 subtraction, the following which of addition, multiplication and division . would you say are commutative ⎠ operations? Notice that adding the this can easily be found arithmetically by 10 corresponding ⎛ 5 ⎞ u + v = ⎜ ⎝ ⎛ 3 ⎞ + ⎟ 0 ⎜ ⎠ ⎝ ⎟ 4 Subtraction components ⎛ 5 + 3 ⎞ = ⎜ ⎠ of ⎝ ⎟ 0 + 4 ⎛ 8 ⎞ = ⎜ ⎠ ⎝ consider the ⎠ – by v is inter preted ‘move along and 5 + 10 10 ÷ 10 – 10 × 5 5 and and 5 5 ÷ – 10 10 5 and 5 × 10 vectors two vectors u = ⎜ ⎝ u 5 ⎟ 4 ⎛ 5 ⎞ Again + together. geometrically negative v’ or u as + ⎛ 3 ⎞ and ⎟ 0 v = ⎜ ⎠ ⎝ ‘move along ⎟ 4 ⎠ vector u’ followed (–v). u u u – v – resultant vector here is u – v and in this specific case subtracting that the u we can easily corresponding find this arithmetically by Subtraction ⎛ 5 − 3 ⎞ ⎛ 3 ⎞ ⎛ v = ⎜ ⎝ ➔ ⎟ 0 − ⎠ Vectors ⎜ ⎝ ⎟ 4 are ⎠ = ⎜ ⎝ ⎟ 0 − 4 ⎠ subtracted = – u ⎝ by not 2⎞ = ≠ ⎜ 2 ⎞ ⎜ is commutative. components. ⎝ − v) ⎠ ⎛ u (– ⎟ 4 v ⎛ 5 ⎞ + . ⎝ again = 2 ⎞ is ⎜ Notice v v ⎛ The – u – v ⎟ 4 ⎠ ⎟ −4 ⎠ adding a negative vector. Chapter Q The zero Consider PQ a + the QR return vector + to triangle RP the must PQR be starting equal point. to zero This is as the written overall as PQ journey + QR + results RP = in 0 P R The zero vector is in bold type to indicate that it is a Equi li brium vector . name ⎜ ⎜ ⎟ = in ⎝ 0 the two dimensions and ⎜ ⎠ where ⎟ 0 in three a are in – their resultant Y ou explore may the a + a = b 2i – b b 3j – + 3k and a b = 2b c 4i – – 2j k, find the vectors: 3a Answers a b a b + – 2b c b a – = (2 + = 6i – = (4 – = 2i + 3a = 1 Given these 2 4)i 5j j 2i – + + + 2)i (2(4) = Exercise (–3 + (–2))j + (3 + (–1))k 2k + (–2 – (–3))j + (–1 – 3)k 4k – 5j 3(2))i – + (2(–2) – 3(–3))j + (2(–1) – 3(3))k 11k G that a = 2i – j, b = 3i + 2j, c = –i + j and d = 3i a + b d a + b Given + a = d ⎛ 2 ⎞ ⎜ ⎟ ⎝ −3 b b + e a – c b c c + a f d – ⎛ −4 ⎞ , b = ⎜ ⎝ ⎠ ⎟ 5 b + a ⎛ −5 ⎞ and c = ⎠ ⎜ ⎝ ⎟ −3 , find these ⎠ + b b b – c (a c 2 d a + Vectors find d 1 a +3j, vectors. a is wish 3b – c e 3c – 2b + 5a + c) vectors. to concept equilibrium that balance ⎟ zero. Example of dimensions. 0 a state number ⎟ forces ⎜ Given the ⎛ 0 ⎞ ⎛ 0 ⎞ 0 for is fur ther . of Given 3 that a = 3i – j – 2k and b = 5i – k, The find these method combined a a + c 2a b – b b b – 2a d 4(a – forces b) + 2(b + c) by the vectors p = 3i – 5j and q = adding –i + since the vectors x, y – 3p = q 4p b – 3y = 7q 2p c + z = x ⎛ The vectors b a and 6 ⎛ and y b are such that a = ⎜ ⎝ ⎞ ⎞ ⎜ + y in − 3 ⎠ that a = in b, find the values of x and his ⎜ vectors BCE). the polymath Greek Aristotle Dutch Mathematician (1548–1620) treatise the Principles which led development was not Caspar The of the been of used the it to a Ar t of of breakthrough a and b are such ⎛ t and ⎜ ⎟ ⎜ ⎟ u ⎝ s ⎞ ⎜ ⎟ t that until around Mechanics. 1800 that y ⎛ 3 ⎞ 6 time called has ⎠ It Given and Stevin Weighing ⎟ −2 x is and more ⎟ x = ⎝ the or 0 Simon 5 them law the two z where and (384–322 2x a of 4j, philosopher find calculating action parallelogram known Given 4 of vectors. (Danish-Norwegian, and Jean-Rober t Argand ⎟ 3s (Swiss, ⎜ ⎟ ⎜ ⎟ ⎝ ⎠ Wessel 1745–1818) t + s 1768–1822) formalize the general star ted to concept of a ⎠ ‘vector’. Given that 3a = Geometrical When you addition, are 2b, Example the values of s, t and u proofs not given subtraction geometrical find specific and scalar vectors you multiples to can still deduce use vector some results. In triangle OXY, of OX, and OY A, XY B and C are respectively , the midpoints OX = x and OY = y X OA a , OB , XY , OC and x CO in terms of x and y A C b Find x an and expression y. between What the is line for the XY AB in terms of relationship and the line O AB? Y y B 2 c P is the point such that OP = OX XP + . Find OP 3 d What can you conclude about the position of P? Answers 1 1 a OA OX = 2 1 OB 2 XY = Use XO infor mation from the diagram. 1 OY = x = 2 y = 2 + OY = −x + y = y − x Use { vector addition. Continued on next page Chapter 1 OC = OX XC + = x Use XY + vector addition. 2 From the diagram, 1 = x + ( y − 1 x) 2 XC XY. = 2 1 1 = x + y x 2 2 1 1 = x + 1 y = (x 2 2 + y) 2 1 CO = −OC = (x + y) 2 1 1 AB b = AO OB + = x + AO y = OA 2 2 1 = ( y − x) 2 1 Since XY = y − x AB and = ( y − x) 2 then XY the and The line in lines AB the are is half same the length direction therefore as of XY. parallel. 2 OP c = OX XB + 3 2 = x + (XO + OB Use ) vector addition. 3 XO 2 = x + + OX y) 3 2 1 = = 1 (−x 1 x + y 3 3 1 = (x + y) OP : OC = 2 : 3 3 So 2 P d lies of the way along the line OC 3 Exercise 1 In this of PQ H triangle and a = OA OA, = b AP, = BQ = 3OB, N is the P midpoint OB. A N Show that a a AP = a c PQ = 4b e ON = a b AB = b d PN = 2b f AN = 2b − a O Vectors − + 2a 2b − a b B Q A 2 In this Show triangle a = OA , b OB = and AC : CB = 3 :1. that a 3 AB a = b − a AC b = (b − a) C 4 1 1 CB c = (b − a) OC d = OABC is a + 4 4 3 4 a OA trapezium. = a, OC = O b B b 4 c, and a A O CB = 3a. D is the midpoint of AB. c D Show that OB a = c + 3a AB b = c + 2a B C 3a 1 OD c = 2a + 1 c OC d = 2a − c 2 2 A 4 ABCDEF is a regular hexagon with center O. FA = a and FB = b a Express a each of these in terms of a and/or b F i AB ii FO iv BC v FD iii B FC b O What b geometrical facts can you deduce about the lines AB E and Using c C FC? vectors, determine whether FD and AC are parallel. D 5 In the diagram OA = a and OB = b. M is the A midpoint of OA and P lies on AB such that a 2 AP AB = M 3 Show P that 2 a AB = b − a and AP = X O (b − B b a) 3 MA = a and MP = If d Prove X is a b − a 6 3 2 c 1 2 1 b point that such MPX is that a OB = straight BX, show that MX = 2b − a line. Chapter . We Scalar often solving need product to find the θ between two vectors when problems. Investigation Consider and angle two = OB b – vectors = 5i + going to use cosine = OA a = 3i rule + 4j 12j B b A a O Y ou are F ind the vector F ind the lengths Recall the the cosine to nd the θ angle between the two vectors. AB of cosine OA, r ule 2 OB and 2 | OA | rule + | OB and AB apply (|OA |, it to |OB | this and |AB |). situation 2 | | AB | = cos θ 2 | OA | × | OB | 2 2 ⎛ | OA | 2 +| OB | ⎞ | AB | −1 θ F ind by nding cos ⎜ ⎟ 2 | OA |× | OB | ⎝ Y ou should Now nd repeat that this θ = ⎠ 14.3º. process using = OA a = a i + a 1 OB = b = b i + b 1 At step 3 it and j 2 is a possible b 1 cos θ j 2 + a 1 to simplify the expression you obtain to b 2 2 = | a | | b | Or a alternatively b 1 a b 1 + 1 a b 2 , is + a 1 called the =| a || b | cos b 2 2 scalar product of the two vectors a = a 2 i + a 1 j 2 The and b = b + i b 1 It can be 2 found coefficients of k ➔ of together Scalar If a = j also by multiplying together and then and the (if adding coefficients in three them all of i together, dimensions) the the i product + a 1 j known and b = b i + 1 b j if a = a i + a 1 j 2 + then a · b = a 2 a k 3 and b 1 + 1 a scalar b 2 = a b 1 Vectors + 1 a b 2 + 2 a b 3 . 3 dot that the product b = b i 1 + b j 2 + b is 2 k then 3 a · b a · b the coefficients Notice 2 as product. commutative, Similarly is up. product a scalar j = b · a that is ➔ The scalar between Example If a = i + product the a b = |a||b|cos θ where θ is the angle vectors. 4j – 2k and b = 2i + 4j + 6k, find a b Answer a b = = (1 2 × + 2) + 16 (4 – × 12 4) = + (–2 × The 6) not 6 result a is a scalar number, vector. Y ou can GDC to product Finding If you you do can the not angle know between the angle θ between |a||b|cosθ = or cosθ θ find rather Example Find b = the 5i of the two your scalar vectors. vectors two vectors a and b then + than resor ting b = a to nd use use a a · b two also to b the full cosine r ule each time. angle between a and b given that a = 3i + 4j and 12j. Answer Using a · b a · b = 3 × |a| = 5, |a| |b| = 5 |a||b|cosθ, + |b| cosθ ⇒ 63 4 = × 12 = 63 13 = 5 × 13 × = 65cosθ = 65cosθ cosθ 63 cosθ = 65 63 1 θ = cos 65 o = 14.25 Chapter Special properties Perpendicular An impor tant of the scalar product vectors fact is that two vectors are per pendicular if and only Perpendicular if their scalar product is are This is because θ if = vectors zero. 90º also called then or thogonal. o a · b = |a||b| cos 90 = |a||b| × 0 Notice = i, 0 j that and k since are all perpendicular ➔ For vectors perpendicular a · b = 0 i · j = j · k Parallel If two j · i = = k · j i · k = = k · i = 0 vectors vectors a and b are parallel then o a · b ➔ = |a||b| = |a||b| For parallel Coincident cos 0 vectors a · b = |a| |b| vectors Since Given a vector i and j and all one unit in i · i = k are a length o a · a = |a||a| cos 0 j · j = k · k = 1 2 = a 2 ➔ For coincident vectors a · a = a In 1686 Newton published Philosophiae Exercise I Naturalis 1 Given that a a · b b b · c a = 2i + 4j, b = i – 5j and c = –5i – 2j, find Mathematica, he detailed laws of a · a d c · (a applying + + to two Given that u ⎛ 1⎞ ⎛ 4 ⎞ ⎛ ⎜ ⎟ ⎜ ⎟ ⎜ 0 = ⎜ , v 3 = ⎟ ⎜ ⎜ ⎟ ⎜ ⎠ ⎝ 5 ⎝ know we how to and w ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ , b u · (v d 2u · w e (u – resultant to of nd forces ⎟ ⎠ w) c u · v – are v) · (u + perpendicular . may wish to u · w explore – and find ⎟ Y ou u · v into 6 1 a force directions ⎟ 3 = a perpendicular that w) fur ther . Vectors these In and 1⎞ the motion. a) · b resolve 2 which b) need (c in three understanding c e Principia these laws 3 Determine parallel or whether these pairs of vectors are per pendicular, neither. ⎛ 1 ⎞ ⎛ 2 ⎞ a a = 2i + 4j and b = 4i – 2j c b = ⎜ ⎝ c u ⎛ 8 ⎞ ⎛ ⎜ ⎟ ⎜ 2 = ⎜ ⎟ ⎜ and v ⎜ ⎟ ⎟ ⎜ ⎟ ⎠ ⎝ 0 ⎜ OZ = ⎟ ⎜ ⎝ 4 Find 5 Given find 6 ⎜ + ⎟ 2 = Find 2 1 c 2i one and EXAM-STYLE 8 9 Consider a AB b AB c the Find the 1⎞ ⎛ ⎟ ⎜ c 2i and b = 3i – 2j – k = 2i – 8j and m = –i + 4j 1⎞ ⎜ if 5k, ⎟ 1 such = a b 5 i 2i + + a · d the j + 7j = 2k and –9, vectors a c = b · d = and b b i = + j 11 if 3i + + k, and |a| 2j c · d = – k = 6. 3, these vectors, giving your answer in place. ⎛ 4 ⎞ ⎜ b ⎠ ⎝ – and 6 between 2i ⎠ = = that ⎟ 0 3 ⎞ ⎛ and ⎠ ⎜ ⎝ ⎟ 1 ⎠ 5j points A(2,4), of 2 the angle between B(1,9) and ⎜ ⎟ ⎜ between these ⎛ 2 ⎞ ⎟ ⎜ ⎜ C(3,2). ⎟ ⎜ 6 ⎝ ⎠ –7j + k Find ⎝ i + j – AC vectors. 4 ⎞ ⎟ 2 ⎜ ⎟ ⎜ ⎟ 2 1 ⎠ and ⎟ and ⎜ and ⎟ of ⎛ ⎟ 3 b ⎟ AB pairs ⎞ 3 and ⎟ 2 ⎝ – b) ⎟ angles ⎜ ⎜ k AC · cosine 2 + AC and the ⎜ 2j QUESTIONS ⎛ a – decimal ⎜ ⎝ 5j n – ⎠ ⎛ 2 ⎞ and ⎠ + = between angles to ⎟ ⎝ d a · b ⎞ ⎜ 3i angle the 2 ⎛ a = and degrees f 3i ⎟ ⎝ vector the CD ⎠ a ⎟ ⎛ and 3b) · (2a that the Find |b| 7 (a = ⎟ ⎝ ⎠ ⎝ a 1 ⎛ 2 ⎞ = d 0 ⎜ ⎜ ⎟ 0 AB ⎠ ⎛ 0 ⎞ and ⎜ g ⎟ 2 ⎠ ⎟ = ⎜ ⎝ ⎠ 1 ⎜ OX = ⎟ 1 = ⎛ 1 ⎞ e 1 d 4 ⎞ 2 ⎝ and ⎟ ⎠ ⎝ ⎠ k Chapter EXAM-STYLE QUESTION 1 ⎛ ⎟ ⎜ 10 Points A, ⎛ 2 ⎟ ⎜ ⎜ 2 ⎞ ⎜ ⎟ ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ C form a triangle. Their position vectors 1 are ⎟ ⎜ ⎟ 4 respectively . ⎠ Find ⎟ ⎟ 1 ⎠ a the lengths b the exact c the area of the value of the sides of the AB and cosine AC of the angle BAC triangle. ⎛ 1⎞ ⎜ 11 Find the angle between ⎟ and 1 ⎜ the x-axis. ⎟ ⎜ ⎟ 1 ⎝ EXAM-STYLE 12 The position 13 a Show b Find λ Find vectors relative that the if ⎠ QUESTION respectively , OA A and to and length the OB of vectors an B are origin are 4i + 4j – 4k and i + 2j + 3k O per pendicular. AB. 2i + λ j + k and i – 2j + 3k are per pendicular. EXAM-STYLE 14 Let a = 5i QUESTIONS – 3 j per pendicular 15 Let a + 7k, to b a p ⎞ ⎛ ⎟ ⎜ 2 and b ⎟ ⎜ ⎜ ⎟ ⎜ value that + λk. Find λ such that a + b is 2 ⎞ ⎟ ⎟ . ⎟ ⎝ ⎠ of Vector Suppose j 3 p . + p = ⎜ the i b ⎜ ⎝ Find = ⎛ = a p ⎠ such that a equation straight line + b of passes and a a b are per pendicular. line through a b A point that A where the line is A has a parallel position to a vector vector a and b a Now if we let R be any point on the line, 0 then AR is Any point parallel R on the to b line L can be found by b A star ting vector a at to the origin reach the then line. moving Now through there must the R be a some number t such that AR = t b r 0 Hence r = Vectors OR , ⎜ ⎝ 1 4 ⎝ and ⎛ and 3 ⎜ B = OA + AR = a + tb ➔ The is vector the general given Example a Find to Find c Find and vector a vector of a parallel vector line is of point to the given a by point on the line. t r on line is = a + the t b where line, a and b called is the is r a a parameter. the the b position position direction of equation vector vector the –i equation + vector 3j – of the line through (1, –1, 3) of the line through the and parallel k equation points A(1, 0, –4) B(–2, 1, 1). the acute angle between these two lines. Answers a a = i The r b = – j + 3k vector (i OA j + b = equation 3k) + –i + + 3j – 1 and OB = 1 OB Write OA – r ⎛ 1⎞ ⎛ ⎜ ⎟ ⎜ 0 = equation ⎜ ⎜ + AB of of the line the ⎟ ⎜ ⎠ ⎝ ⎠ 1 vectors 3 are 3 1 and To 5 find a b = + 3 between × 35 × the these 1 = cos θ = 35 11 two angle 1 + –1 × lines between cos θ direction vectors. 5 r the = a equation + t b, direction ⇒ angle |a||b|cos In 11 the their = line. ⎟ find –3 direction ⎟ 1 × the 5 –1 in 1 ⎜ direction Using is ⎟ t ⎟ The B. is c and 3 ⎞ 4 ⎝ A 5 the position 3 Hence of 1 = the vectors 1 = k k) AB – 2 4 3j is t (–i 0 = and b is the vector. cos θ 1 11 35 1 –1 θ = cos = 11 35 87.1° Chapter Exercise 1 Find J the through equation point B a = ⎜ ⎝ b a = 2 c a = ⎜ 5 ⎞ ⎜ ⎟ 2 = ⎛ 3 ⎞ ⎛ ⎜ ⎟ ⎜ b ⎟ ⎜ d 2 a Find the 3 = a ⎟ ⎜ ⎟ ⎟ 2 ⎠ – j ⎝ + (4, 5) c (3, 5, 2) an passing k b a = and b a = and of 2 point = 5 ⎞ ⎜ ⎟ 2 3 = ⎜ ⎠ ⎜ b ⎜ ⎟ ⎜ ⎠ ⎝ – line B + r (5, –2) r (–3, 5, 1) = r (2, 1, 1) p = ⎜ = ⎟ 1 ⎜ given Vectors b as and given. t ⎠ = ⎟ 1 ⎜ ⎝ r = t –2i + q so ⎛ ⎜ 5 3j + that given line. ⎟ 3 ⎝ ⎟ of the 4 ⎞ 1⎞ − on + ⎠ ⎜ ⎜ 2i lies ⎟ 2 ⎛ + ⎠ ⎜ point ⎛ 1 ⎞ + ⎛ equation and vector vector a 5k t ⎠ 1⎞ ⎟ 0 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ 3 direction position to ⎠ the ⎝ Find per pendicular (1, –1, 0) ⎠ ⎜ the and ⎟ whether (4, 5) Find (0, 0, 1) ⎟ b ⎝ 5 d (5, –2) ⎠ ⎛ 5 ⎞ d and ⎟ 4k ⎝ c (4, –2) with ⎛ 2 ⎞ b b 1 3j Determine a through 2 = ⎟ 1 ⎝ 4 passes ⎛ 4 ⎞ 0 i which ⎟ 0 ⎝ ⎟ = = line 1⎞ ⎛ b ⎞ ⎜ a the ⎟ 6 ⎝ ⎛ ⎜ d k 1⎞ ⎜ ⎠ ⎜ the ⎛ b ⎟ ⎛ a of – (2, –4, 5) through ⎝ c 2j (3, –2) equation ⎜ ⎝ = equation ⎛ 3 ⎞ a ⎠ points. a Find ⎠ ⎜ vector two given. 1 = ⎟ 3i as passing 3 ⎞ 8 ⎝ b and ⎟ 0 ⎝ 2 vector vector a ⎠ ⎜ ⎠ ⎜ position to 1⎞ ⎛ b parallel ⎟ 2 ⎝ ⎠ ⎛ ⎝ = line 1⎞ ⎛ b ⎟ the with ⎛ 3 ⎞ a of ⎟ ⎟ 2 j − the 3k ⎠ + line t (−2j −3k) through the point (2, 4, 5) 8k the point (p, 10, q) lies on this line. in the 6 Find the point 7 Are vector the parallel lines r or = per pendicular, ⎜ + ⎟ 1 4 ⎝ s ⎠ r = ⎜ + ⎟ 1 5 ⎝ s ⎠ r = ⎜ 2 ⎞ ⎜ ⎟ 1 4 ⎞ ⎟ s 1 ⎠ ⎜ = ⎜ s 1 ⎠ ⎜ ⎜ ⎝ Find + ⎟ 7 the s ⎠ 9 ⎞ ⎜ ⎟ 10 ⎜ ⎝ angle = ⎟ 1 ⎜ ⎝ equations coincident, 6 ⎞ ⎜ ⎟ 3 ⎝ ⎠ ⎛ 1 ⎞ + t ⎠ ⎟ t ⎠ ⎜ ⎝ ⎟ 2 ⎠ 8 ⎞ ⎛ + t 3 ⎠ ⎜ ⎟ = ⎜ ⎟ 6 ⎝ ⎛ 2 ⎞ r ⎟ 3 ⎠ ⎛ 1⎞ + t = ⎜ ⎠ ⎝ ⎟ 1 ⎜ ⎟ 6 and r ⎛ 4 ⎞ ⎛ ⎜ ⎟ ⎜ 7 ⎜ ⎟ ⎜ ⎝ ⎝ ⎠ EXAM-STYLE points 1⎞ ⎟ + t 3 ⎟ ⎜ ⎟ ⎜ ⎟ ⎟ 2 2 ⎟ = 1 r lines. 1 4 ⎟ ⎠ of 2 ⎞ ⎜ ⎟ 3 2 10 = and ⎠ ⎜ ⎝ ⎜ 0 t ⎜ 1 ⎛ 4 ⎞ + pairs ⎛ t ⎝ ⎠ these 0 ⎠ 2 4 2 ⎛ 5 ⎞ r between 1 ⎝ ⎠ 4 ⎞ 1 3 1 ⎠ ⎝ ⎠ QUESTIONS A and B have coordinates (–2, –3, –4) ⎛ 1⎞ ⎜ respectively . The line l has equation r ⎜ ⎜ and ⎜ + t ⎝ that point A lies on ⎟ 2 ⎟ ⎜ ⎟ ⎜ 2 Show (–6, –7, –2) ⎛ 1 ⎞ ⎟ 1 = 1 a the these? ⎛ + ⎛ 5 ⎞ r ⎠ ⎜ ⎝ The ⎛ ⎛ 2 ⎞ = ⎠ ⎛ = = 2 2 9 of 2 ⎟ ⎝ ⎛ 5 ⎞ = r through 2 1 b none ⎛ 1 ⎞ + ⎟ ⎝ r or = r ⎟ 3 ⎝ ⎛ 2 ⎞ a vector ⎝ 1 8 passing 2 r r line these 4 ⎞ ⎛ + ⎟ ⎝ e ver tical by ⎠ ⎜ 2 r 1 d a 2 ⎛ ⎝ ⎛ 5 ⎞ c ⎛ ⎝ ⎛ 2 ⎞ b of represented ⎛ 3 ⎞ a equation (–6, 5). ⎟ ⎟ 6 ⎠ ⎝ ⎠ l 1 b Show that AB is per pendicular to l 1 10 The OC figure = 5 m shows and a OD cuboid = in which OA = G 2 m, F 3 m. 5 m Take in O the as the origin direction OA, and OC unit and vectors OD i, j and k respectively . D C B E a Express these vectors in terms of the unit 3 m vectors. O 2 m i b iii |OF Find Hence the | ii the find A AG ii Calculate i c OF value |AG scalar the of | product angle of between OF the and AG diagonals OF and AG Chapter Relative 11 vectors to i a + fixed 5j – Find the vector b Find the cosine c Show that, A (1 and Find e Hence to the work are out of for all 7)i + value find 3j points + angle A and B have position respectively . OAB values (5 – of the μ of 8)j for point point + , the (–2 which on of given the vector where the lines Example the point P + 8)k OP foot two with lies on position the line through is of per pendicular the to AB per pendicular from vectors equations lines of two different lines, you can cross. 3 0 Two 6k AB Intersection you the – B d O + O, 8i AB a vector If point 2k and have equations r = 1 + s 6 1 and 1 r 1 1 2 = 2 0 + t 0 4 . 8 In three two Show that the lines intersect and find the coordinates of the point dimensions, lines will either of 1 intersection. intersect the value – of if the Answer variables Two vectors their corresponding are equal if and r r 1 components are equal. is intersect if there consistent 2 a value of t and x r 3 y = 1 = 0 + s 3 + value s of s such ⇒ y = z = s x 6 1 = 1 1 + be parallel 2 will s have vectors 1 2 + multiples + y = 2 + z = 8t 4t 8 be skew lines are = – s = 6 (1) 2 + 4t (2) + s = Equate and 8t (3) (1) gives s = the components solve the are not resulting simultaneous so equations. the Equation the not and consistent –1 if values s of other parallel 3 are 6 3 0 = each ⇒ z direction that x 4 t they 0 = y = 2 – r scalar r all equations that 2 r 1 z = 1 in a three x is lines do not 3 intersect. Substituting 3 = 2 + 4t s = 3 so into t equation (2): A = Q 4 B Substituting – 1 + 3 = s = 3 8t into so equation t (3): = 4 Since the value of s and the O value of t AB consistent for all three equations the must intersect. { Vectors and PQ are skew two – lines P are Continued on next page they never meet. Substituting s = 3 into r To : find the point of 1 r ⎛ x ⎞ ⎛ 3 ⎞ ⎜ ⎟ ⎜ ⎟ y = ⎟ ⎜ ⎜ 0 = ⎜ 1 ⎟ ⎜ ⎠ ⎝ 3 + ⎜ ⎟ value 1 ⎟ ⎜ ⎠ ⎝ y z = = = of + 3 = 6 0 + 3 = 3 + Therefore of = the ⎟ ⎛ x ⎞ ⎛ 6 ⎞ ⎜ ⎟ ⎜ y 2 2 = are (6, ⎜ ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ give of the of in intersection. 3, of the point 2). ⎜ ⎟ 4 ⎜ ⎟ ⎟ ⎜ ⎟ ⎠ ⎝ Alter natively we could 4 8 0 z ⎝ substitute ⎠ into x = = 2 the + 4 ⎜ ⎛ 0 + 8 = 3 This gives the 1 and is a ⎞ = ⎟ 4 2 useful way of checking ⎠ the Exercise same ⎠ ⎜ ⎝ Find t ⎞ ⎟ 4 coordinates = of 2 1 ⎝ z value r 6 ⎛ y 1 to ⎛ 0 ⎞ 1 + ⎟ r vector 2 ⎟ ⎜ into position ⎠ coordinates intersection = r 3 s 1 the 1 3 –1 the ⎟ point x substitute ⎟ ⎜ 1 z ⎝ intersection ⎛ 1⎞ answer. K the coordinates of the point where r = 4i + 2j + λ(2i – 4j) 1 intercepts = r 11i + 16j + μ(i + 2j). 2 2 The vector equations of two lines are given by r = ⎛ 4 ⎞ ⎜ ⎟ 1 ⎝ ⎛ and r = ⎜ 2 ⎝ position 6 ⎞ 3 The line + l t ⎠ ⎟ . ⎜ ⎝ vector EXAM-STYLE ⎠ s ⎜ ⎝ ⎟ 2 ⎠ ⎛ 9 ⎞ ⎟ 3 2 ⎛ 8 ⎞ + of 6 The lines intersect at the point P. Find the ⎠ P QUESTIONS has equation 1 r = ⎛ 5 ⎞ ⎛ ⎜ ⎟ ⎜ 1 ⎜ ⎜ + 2 ⎞ ⎟ t 1 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ ⎟ ⎟ 2 ⎝ The 1 line l ⎠ has equation 2 r ⎛ 3 ⎞ ⎜ ⎟ 2 = ⎜ ⎜ ⎛ 2 ⎞ ⎜ + s ⎜ ⎟ ⎜ 4 ⎝ Show ⎟ 1 ⎟ ⎟ ⎟ 2 ⎠ ⎝ that the ⎠ lines l and 1 the point of l intersect, and find the coordinates of 2 intersection. Chapter 4 Find where the lines with equations r = i + j + t (3i – j) and 1 = r –i + s j intersect. 2 5 Show that the two straight lines r ⎛ 3 ⎞ ⎛ ⎜ ⎜ ⎟ 0 = ⎜ 1 ⎜ + 1⎞ ⎟ t 1 ⎟ ⎜ ⎟ ⎜ ⎝ ⎛ 1 ⎞ ⎜ r ⎟ ⎟ ⎜ + 1 ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎠ ⎝ 0 6 The L: l M: a m b 7 3i = are skew . 2j – + vector s (–i 6k lines of the has have + the point that L 5k 20j that their line + M + 3j equations – 5k) + t (3i – 4j L and M – 3k) meet and lines L equation and r M are ⎛ ⎜ ⎜ = ⎟ 9 ⎝ A The point B The points Find Point 8 P Find c Hence The b a = A – coordinates and lies B on lie of L on a + A – the and such 2 ⎜ ⎟ ⎜ ⎟ ⎟ k Determine have vector ⎠ ⎝ line ⎠ where a is where b a constant. is a constant. L. b. OP is per pendicular to L P distance OP . position respectively , a 2 (b, 13, –1), that of exact B vector ⎟ t ⎟ (5, 7, a), the and coordinates find 2j coordinates values the points 3i has the b has position 1⎞ 3 point the per pendicular. ⎛ 6 ⎞ ⎜ The find intersection. ⎜ a ⎠ ⎠ and 14i Show The L – Show of ⎝ 1 lines = ⎠ ⎟ s ⎜ ⎝ 2 ⎛ 1⎞ 4 = 2 and ⎟ 5 vectors relative equation of to a the a = fixed 2i – j + 2k and origin O line L , passing through 1 A and The B. line L has vector equation r = 7i + 3k + s (2i + j + 2k). 2 b Show that the lines L and L 1 vector c Find d Find, of the the point length of of the intersect and find the position 2 intersection line C AC Extension to the nearest degree, the acute angle between the lines a L 1 Vectors and L 2. material Workesheet line in 12 three - on CD: Equation dimensions of . Applications Vectors are quantities Example The applicable such as to of vectors real-life situations displacements and that include vector velocities. position vector of a boat, A, t hours after it leaves a harbour is 30 given by r = t . second boat, B, is passing near the harbour. Its 15 position A 1 vector 50 at time t is given by r = 10 + t 2 5 a How far leaves b How c Are apar t the fast the change are the two boats at the time the 10 first boat harbour? is each boats boat in traveling? danger of colliding if one of the boats does not course? Answers 0 a At t = 0 boat A is at the ‘origin’ with position vector 0 50 and boat B has position vector 2 them b The is 50 speed their therefore 5 the distance between 5 + 5 of = the direction = 2525 boats vectors is – 50.2 found this is km. by calculating each boat’s the magnitude velocity of vector. 30 For boat A the vector that it will pass through in one hour is 2 which has length 15 2 30 + 15 = 1125 = 33.5 km. –1 Therefore boat A has a speed of 33.5 km h 10 For boat B the vector that it will pass through in one hour is 2 which has length 10 10 2 + 10 = = 200 14.1 km. –1 Therefore For c the that boats the B to has a speed collide position there vectors x components: 30t = 50 y components: 15t = 5 Therefore Exercise 1 boat the boats of + + will the 10t not 14.1 km h would 10t two ⇒ t t = need boats = . to be are a value the of t such same. 2.5 h 1 h collide. L The position vector of ship The position vector of buoy What of S is B 30 is km 20 nor th km and nor th 60 and km 45 east. km east. is a the position b the exact of the distance ship from relative the to ship the to buoy the buoy? Chapter 2 A par ticle with P is constant vector ⎛ x ⎞ ⎜ ⎟ y ⎝ at the origin velocity and O at time t arrives at = the 0. The point par ticle Q with moves position ⎛ 20 ⎞ = ⎜ ⎠ ⎝ ⎟ −8 a the velocity b the position the same m 4 seconds later. Find ⎠ of P of P if velocity it continues for 6 more moving past this point with seconds. –1 3 Another par ticle It through passes Find the speed Find the distance e Will In this the vector 3 p.m. on velocity of traveling the b 4i time the by r point ⎛ ⎜ ⎜ ⎟ 3 + ⎜ ⎟ Find b Show c Find + are the the by the 3i in t = 3 is (4i 5j) m s – j) m at 3i + 3j 3j. ships of Ship + of 2j = is time in hours. 1 km. a A ’s and and it cliff looking position is given relative traveling by 4i + out 3j with and to sea to a a it is Find will collide if one does not will collide. helicopters X and Y at time t seconds are given 0, and y ⎟ 2 ⎟ 7 t the in of distance 9 metres. the two respectively . 2 given 1 a vector –1) are two helicopters. helicopters between do the not meet. helicopters when t = 10. method that the points A(1, 2, 3), B(–2, 3, 5) collinear. QUESTION points and 1 exercise using the t s. kilometres top position ships ⎞ speed that the C(7, Vectors given on two ⎟ ⎜ EXAM-STYLE 2i when displacement of 4 a Show 1 ⎜ Review 2 two −1 t ⎟ Distances and which of 3 Prove are B’s the vector – formulae ⎜ 1 which O traveling. velocity position (12i collide? given Ship velocity QUESTION ⎛ 11 ⎞ = a at position the x at 3j. whose from a ships is constant par ticle. T standing two + A with course EXAM-STYLE The is shore with change the of distances man the of represents obser ving point a a point par ticles question unit and two moving the d At ✗ is c A 4 T –3i – A, 5j B + and 8k C with position respectively vectors form a 5i j + right-angled 6k, triangle. 0. EXAM-STYLE 3 Given QUESTION that a ⎛ 5 ⎞ ⎛ ⎜ ⎟ ⎜ = and 1 b 1⎞ ⎟ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎠ ⎝ 4 + b Two and a lines b with are point EXAM-STYLE 5 A triangle P. the vectors per pendicular. equations r ⎛ 0 ⎞ ⎜ ⎟ = Find the + 6 ⎛ 7 ⎞ ⎛ 3 ⎞ ⎛ ⎜ ⎜ ⎜ s ⎟ ⎜ ⎜ ⎟ ⎜ ⎠ ⎝ 1 ⎟ and 3 ⎜ ⎝ the that ⎠ 1 at show 5 3 ⎝ a , 3 = ⎜ r = 2 ⎟ of + 1 ⎜ ⎟ ⎜ ⎠ ⎝ 1 coordinates ⎟ 2 ⎞ ⎟ t intersect 4 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ ⎟ ⎟ 2 1 ⎠ P. QUESTIONS has its a Find AB and b Find AB · c Show ver tices at A(–2, 4), B(1, 7) and C(–3, 2). AC AC 3 that cos BÂC = 2 5 6 6 Two lines L and L 1 are given by 1 2 2 2 s 2 3 a P b Show is the point on L when s = 4. 2 the 12 1 Find and 0 t 1 11 7 position vector of 3 P 1 that P is also on L 2 2 ⎛ 7 The line L has vector equation r ⎟ ⎜ −3 = 1 ⎛ 1 ⎞ ⎞ ⎜ + t is parallel to L 2 a and passes . ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ 3 L ⎟ 3 ⎜ through 2 the point B(2, 2, 4). 1 Write down a vector equation for L in the form r = a + s b 2 ⎛ 3 ⎜ A third line L is per pendicular to 3 L and is represented by 1 r ⎟ 11 = ⎛ 7 ⎞ ⎞ ⎜ ⎜ ⎜ + q ⎜ ⎟ ⎜ 7 ⎝ b Show c Find that the x = of the point C, the intersection of L BC e Find |BC | in ⎠ and 1 Find ⎟ ⎟ 1 ⎝ ⎠ –3. coordinates d ⎟ x ⎟ the form a b where a and b are integers to L 3 be found. Chapter EXAM-STYLE 8 (In this question hours.) Ship QUESTION At A ’s distances noon a position are lighthouse at time t is measured keeper given in km obser ves by 1 two 4 3 and B’s position at time t is given by r 2 9 Show a will In that A occur order to and and B the prevent will collide, position collision, and vector at find of 12:15 the ship A and B. 12 5 time point in 17 the A 4 4 Ship ships time of when this collision. changes its 16 direction . to 17 Find b the Review distance between A and B at 12:30. exercise 2 3 1 Find the size of the angle between the two vectors and Give your answer EXAM-STYLE 2 The 3 OP of the OQ , 3 A tent defined 1 = are OR and 1 and OABCDE section that is ˆ PQR c triangular prism b is an a the position vectors . Find 5 0 QP by 2 = 1 3 PQR QR 4 degree. a nearest triangle 2 = the 5 QUESTIONS vertices to . equilateral the triangle area with with a of triangle constant sides of PQR cross- 2 m. The E tent 2 m 4 m is 4 m long. The base OADC is horizontal. Suppor t poles are to be C D laid along Take OA O and the as the OC diagonals origin BC and respectively , and unit k is BD B vectors a unit i and vector j in the directions ver tically of 2 m 4 m upwards. O A 2 m i, a OC i Hence c Calculate d find i |BC iii the Hence OB ii b vectors the | values scalar find BD | product the k of |BD ii and and OD iii BC j angle BC of BD and between the . suppor t poles. 2 4 Given is a that scalar a = + variable, a the values b the angle Vectors xi of x (x − 2)j + k and b = x i − 2x j − 12x k find for between which a and a b and b when are x = per pendicular −1. where x EXAM-STYLE 5 The QUESTIONS points P and Q have position ⎛ 1⎞ ⎜ ⎟ ⎛ 1 ⎞ ⎜ 1 vectors ⎜ ⎜ ⎜ ⎟ ⎜ ⎠ ⎝ 3 ⎝ ⎟ 5 and ⎟ ⎟ ⎟ 5 ⎠ O OP a Show that b Write down is the per pendicular vector to equation PQ of the line L , which passes 1 through The line P and has L Q equation r 2 2 1 1 3 2 Show c that the lines L and L 1 vector of their Calculate, d lines to and L the All intersect and find the position 2 of intersection. nearest degree, the acute angle between the L 1 6 point 2 2 distances in this question are in metres and time is in seconds. An at is insect point at a flying with point Find The is A at a constant coordinates (0, height. 0, 6). At Two time t = seconds 0, the later insect the is insect B vector insect AB continues to fly in the same direction at the same speed. b Show that x 0 y vector t of = 3 vector of the insect is given by 0 0, the a bird bird at takes time off t is from given the by ground. ⎛ x ⎜ ⎜ down the coordinates of the position ⎞ ⎛ ⎟ ⎜ ⎜ = ⎟ + t 18 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ z ⎝ The ⎛ 36 ⎞ y Write time t ⎜ c at 1 6 time position t 0 z At the ⎟ . 4 ⎟ ⎜ ⎟ ⎜ ⎠ ⎝ 0 star ting 3 ⎞ ⎟ ⎟ 1 position ⎠ of the bird. d Find The the bird speed reaches of the bird. the insect the bird e Find the time f Find the coordinates at point C takes of to reach the insect. C Chapter CHAPTER Vector: ● A A is vector scalar The unit a of is Examples ● SUMMARY basic Examples ● 12 concepts quantity vectors a are quantity of scalars vector in that size (magnitude) displacement that are the has has size distance direction and of and but and direction. velocity . no direction. speed. the x-axis is i. ⎛ 1 ⎞ ⎛ 1 ⎞ In two dimensions i = ⎜ and ⎜ ⎝ in three dimensions i ⎟ 0 ⎟ 0 = ⎜ ⎠ ⎟ ⎜ ⎟ 0 ⎝ ● The unit vector in the direction of the y-axis is ⎠ j. ⎛ 0 ⎞ ⎛ 0 ⎞ In two dimensions ⎜ and j = ⎜ ⎝ in three dimensions j = ⎟ 1 ⎠ In three the dimensions z-axis is k, the ⎟ ⎜ ⎝ ● ⎟ 1 ⎜ unit vector in the direction ⎟ 0 ⎠ of where ⎛ 0 ⎞ ⎜ k ⎟ 0 = ⎜ ⎟ ⎜ ⎟ 1 ⎝ ● The ● If ⎠ vectors i, j, k are called base vectors ⎛ a ⎞ 2 AB = ⎜ ⎟ then = ai + b j = ai + b j + c k |AB | 2 a = b b ⎛ a ⎞ ⎜ ⎟ 2 If AB = b ⎜ then |AB | = a 2 b 2 c ⎟ ⎜ ⎟ c ● Two vectors magnitude; vectors ● Y ou ● Two So, ● can The their write and can i, AB are RS also point equal if they have the j, k components as – BA same are direction equal too, and and so the their parallel are be with if one parallel written as if a coordinates is a AB = (x, scalar = k RS multiple where k of is the To find vector the of A column a other. scalar quantity . kb y) has posi tion vector OP = ⎛ x ⎞ ⎜ ⎟ ⎝ ● same equal. vectors AB This are are resultant from the vector AB position between vector of two points A and y B, = x i + y j ⎠ subtract the position B. Continued Vectors on next page ● If A = (x , y 1 , z 1 ) then OA = a = x 1 i + y 1 j + z 1 k 1 A and if B = (x , y 2 , z 2 ) then b = OB = x 2 i + y 2 j + z 2 k 2 b AB = AO – a OB + a B = OB − OA b = b − a O = − (x x 2 )i + (y 1 − y 2 )j + (z 1 − z 2 Distance AB (x = A vector of length 1 ● A vector of length k ● The and resultant placed u next + ) in ( y y 2 the in each + is the head of of of third to z 2 direction v, other (z direction the u 2 ) 1 subtraction vector, to 2 1 ● Addition x 2 )k 1 2 ) 1 a is found by using the formula a is found by using the formula k vectors side of the triangle formed when u and v are tail. v v u ● Vectors Scalar ● Scalar If a = are subtracted a negative vector. product a i + a if a 1 j and b = a b 2 b 1 + a i a 1 b 2 + + a + b a k ● For perpendicular ● For parallel ● For coincident a · b = a b 1 b = b 3 b = vectors vectors then and i + 1 b + a 1 j b 2 + b 2 k . 2 then 3 3 a product j 2 + b 3 The j 2 a 2 ● scalar i 1 = 1 = adding product Similarly a · b by a b = |a||b| a b = cos θ where θ is the angle between the vectors. 0. |a||b|. 2 Vector ● The a equation vector point vectors on direction equation the line, vector a a a of of is a a parallel = a a line line is given to . the r = a + position line. t is t b where vector called of the r a is the point general on the position line and b vector is of a parameter. Chapter Theory of knowledge Separate Mathematics ■ List the is or often different connected? separated fields of into different mathematics topics, you can or fields think of knowledge. of. ■ Algebra and Geometry lly o and used al proper ties. Making Making connections connections between seemingly different e mathematician René Descar tes (1596 French one of t e key etr y. arated, ces each mutual forces, Joseph Proving Louis and have Lagrange, Pythagoras’s marched have together 1736–1813, their French progress been have united, towards they is a right-angled prove Pythagoras’ show that a² + b² can theorem we = c² knowledge: links Separate or bra alge etry geom when a b of the need the Theory see triangle. are lent theorem c to have mathematician ween b et T o slow perfection.” You Here been connected? used e sam to and they le tack . lem prob G EOMETRIC PROOF c a Draw and cut out four triangles identical to this one. b a Arrange them to make a square with side lengths a + b like b this: a c What is the area of the white square in the center? b c c b c a b b Rearrange square with What the triangles the are same the to make side areas of length, the a a another two like white c a this: a squares? c The area of the central square in the rst b b diagram areas must of the be two equal to squares the in sum the of the second b diagram. A That is c² LGEBRAIC = a² + a b² PROOF a Use the same diagram, but look at the triangles b instead a of the squares. c b c Use these with side two methods lengths a + for nding the area of the large square b. c b c Method . Square Method . Calculate and Methods large 1 and 2 the add both side the this give lengths: area to of c², (a the the + four area expressions for a b)² congr uent of the the triangles b a square. area of the square. Equating these gives b² + 2ab + a² = 2ab + c² ⇒ a² + b² = c² c V ECTOR PROOF a Represent a, b and the sides of the right-angled triangle by vectors c b Because they form a triangle, a So + (a b + = b) c (a + b) b + b = c c Expanding this gives a a + a a + b b = c Which proof a b = b a = 0, because a and b are a or a² did you of prefer? perpendicular So method c a + b b = c Which was the c easiest? + b² = c² Which was the most beautiful? Chapter Circular CHAPTER functions OBJECTIVES sin 3.2 Denition 3.2 Exact cosθ of sinθ and in terms of the unit circle; tanθ denition of as and multiples cos values of trigonometric ratios of 0, 6 2 3.3 The Pythagorean 3.3 Double-angle 3.3 Relationship 3.4 The 3.4 Composite 3.4 T ransformations 3.4 Applications 3.5 Solving circular both Y ou 1 the the sin 30° e.g. Find of for of the 4 3 their 2 and cos x form = 1 cosine ratios and f (x) tan x = a sin (b(x + c)) + d functions equations in a nite inter val, analytically how values of to: Skills cer tain 1 exact value of sin 30°. value of tan check Find the exact value of a sin 45° b tan 60° c cos 150° d sin 225° 0.5 exact 2 tan sin trigonometric trigonometric and sine sin x, , 2 ratios. = the cos , start know exact Find functions trigonometric trigonometric e.g. between functions you should Find identities graphically Before identity , Find exact value sin −1 of a = the tan b c 2 Work with the graphing functions cosπ sin d of your GDC. 3 e.g. Use the graphing functions of Use to GDC to find the x-intercepts the of 3 of f (x) = x functions of your GDC find the x-intercepts of the graph of the each graph graphing your function. 2 − 3x + 2. 3 a x ≈ −0.732, 1, 4 e.g. Use the graphing functions GDC to (x) = 2x 2 − x + 5 b f Use solve the the graphing functions solve each Circular 7 = functions ln(x 2ln x. x ≈ of your − 3) GDC equation. − = equation 2 4x (x) of to your f 2.73 0.0303, 1.38 a 4 − = + b x 2 = 3 − x The London opened carr y to up average The the to 3.5 Eye Eye, 25 on public the in people. million makes south the It is bank year a visitors 2000. major each approximately of the River Each tourist of Thames, the 32 attraction, was capsules and has can an year. one revolution ever y 30 minutes. It is Circular 1.1 Functions y 0.30103 about 135 capsules height metres travels above tall in the a at the circle boarding highest in a point. complete platform can A passenger revolution. be modeled in The by one of 150 the passenger’s the function x 0 1 2 30 0 h t 67.5 cos where h t is the 15 30 height 67.5 , in [ metres, and t is the time in minutes after a This of is the which passenger boards the capsule. This is an example of a the graph function models passenger ’s function, which you will study in this chapter. the circular above the height boarding platform. Chapter . In this ➔ Using section, The unit the we uni t will circle circle continue has its to center work at the with the unit circle. Remember y origin that B(cos i, sin i) (0, 0) and a radius length of 1 the unit. unit circle 2 equation The terminal side of any angle θ position will meet the at a point with y = unit x In coordinates this (θ) is diagram, in AÔB standard (cosθ, sinθ). position. The Look at some angles in standard position in the unit point A the angle positive in θ opens x-axis), degrees or in in then θ a counterclockwise is positive. These direction angles can (from be r 3 3 B r A(1, 0) A(1, 0) 3 x x 0 y 7r 6 A(1, 0) 335° A(1, 0) x 0 0 7r B(cos If the x 7r , sin 6 B(cos 335°, sin 335°) ) 6 angle positive θ opens x-axis), in then θ a is clockwise direction (from the negative. 4r (cos (– 4r ) B 3 , sin (– )) 3 A(1, 0) 0 A 0 –80° x x 4r 3 B(cos –80°, sin –80°) Circular functions the point B has coordinates measured y 0 and (cosθ, sinθ). r (1, 0), the radians. B(cos 45°, sin 45°) has circle. coordinates If 1. A(1, 0) 0 circle 2 + in i standard x has If we know numerical the unit the sine and coordinates cosine to the values point for where an angle, the we angle can give meets circle. y 1 B ( , 2 2 ) √2 √2 2 2 B 135° A(1, 0) 0 A(1, 0) x 30° Investigation – sine, unit Y ou can cosine also use values Sketch each sketch (not tangent Angles of in of the angle each unit angles your in x 0 standard GDC) to help and to help you terminal position you understand sides on on unit the on the the the x- circle. sine, sine and Use cosine and y-axes. your and angle. degrees: 90° 2 180° 3 270° 4 360° 5 −90° 6 −180° 9 π 12 4π in lie the determine 1 Angles tangent circle circle whose cosine radians: 0 7 8 2 3 3 10 11 2 In 2 Chapter the exact Y ou and will 11, you values now of used sine, extend right triangles cosine this to and to help tangent include other you for find 30°, special 45° angles and in 60°. degrees radians. Angle measure degrees, 0°, 0 Sine Cosine Tangent 0 1 0 radians radians 1 1 3 3 It = is impor tant for you 30°, 2 6 3 3 2 to remember values, 1 2 1 = 45° 4 = 1 2 2 required 1 = 2 2 will know be them using your GDC. 3 60°, 3 you to 1 without 3 as 1 = 2 2 2 these 3 1 1 90°, 0 undened 2 Chapter In Chapter same sine cosine For 11, you sin 30° will trigonometric Consider x-axis. also that found supplementar y that these angles the values, sine and angles positive, use you in the the and = the sin150°, unit in each and circle to quadrant coordinates cosine quadrant, cos150° find have the opposite other see that the that unit angles form circle in cosine in the the values angles the different with same ‘related’ angle the quadrants have For is (–x cosine (x y) y) the and related angles quadrant, is cosine i in the the values first sine are and both positive. x i (–x, –y) third sine are with cosine second i angles −cos 30°. represent i quadrant, = values. sine the can on negative. For angles have values. angles As sine For discovered Y ou values. example, Now , you value. (x y) For and angles quadrant, both positive, negative. in the the and fourth cosine the is sine is negative. ➔ For any θ, angle , where cosθ ≠ 0. It follows will the be that, positive, tangent will Example Find a for and be for in the angles first in and the third second quadrants, and four th the tangent quadrants, negative. three sine angles other angles with the same value as: 35° b cosine c tangent 35° 35°. Answers a To find angles with the same sine: Angles with the same sine values meet y the 145° unit circle at points with the same 35° y-coordinates. –325° –215° T o find angles with the same sine values, x draw a horizontal line across the unit circle. These a sin 35° = sin 145° = sin (−215°) = 35° sin (−325°) x-axis. { Circular functions Continued on next page angles angle all with form the To b find angles with the same cosine: Angles meet –325° 35° same T o x with the find unit 325° same circle cosine at points values with the x-coordinates. angles values, –35° the unit draw with a the vertical same line cosine across the circle. cos 35° = cos 325° = cos (−35°) = cos (−325°) These a To c find angles with the same 35° angles angle all with form the tangent: x-axis. y Tangent values are positive in the first –325° and third quadrants. 35° T o find angles with the same tangent x values, draw a line through the origin of 215° the unit circle. –145° These a 35° angles angle all with form the tan 35° = tan 215° = tan (−145°) = tan (−325°) x-axis. This ➔ last For example any sin θ = 2 angle sin(180 − = cos(−θ tan θ = tan(180 Sketch illustrate some useful proper ties. θ: cos θ Exercise 1 helps θ) ) + θ) A each angle in standard position on the unit a 75° b 110° c 250° d 330° e −100° f −270° g −180° h 40° Sketch each angle in standard position on the unit circle. circle. These a b c a 4 the a three given 60° Find g 35° other radians. −2π h 3 angles (in degrees) with the same sine as angle. b three given in the measured d f Find are e 3 angles other 200° angles c (in −75° degrees) with d the 115° same cosine as angle. b 130° c 295° d −240° Chapter Find 5 the a three given 50° Find 6 other the angles 100° b three given degrees) other c angles (in 220° radians) the same c three given −25° d with the same 4.1 rad −3 d other angles (in radians) with the as rad same cosine as 1 b rad c 2.5 rad d Find three given other angles (in radians) with the same tangent as angle. a 1.3 b rad c Example Given −5 d rad a sine angle. a the as Find 8 tangent b the with angle. a 7 (in angle. that sin 50° cos 50° = 0.766 (to cos 130° b 3 significant c figures), sin 230° find the values of cos (−50°) d Answers 2 sin a 2 50° + 2 cos 50° = 1 Use 2 θ sin + cos ‘Pythagorean Section 2 (0.766) cos = 1 50° = 1, the found in 11.3. 1 2 50° = 2 + 2 cos θ identity’ − Substitute (0.766) solve for sin 50° = 0.766, then cos θ 2 cos 50° = cos 50° = 1 0.766 ±0.643 (3 sf) b (–0.643, 0.766) (0.643, 0.766) 130° It is a sketch good of strategy the angles to make on a a unit 50° circle. This makes the relationships x between cos 130° = −0.643 the angle Circular functions to see. (3 sf) { easier Continued on next page c y Use similar sketches to help answer (0.643, 0.766) par ts c and d 230° 50° x (–0.643, –0.766) These sin 230° = related angles all −0.766 make with d an the angle of 50° x-axis. (0.643, 0.766) 50° x –50° (0.643, –0.766) cos (−50°) Exercise 1 Given each a = 0.643 B that sin 70° = cos b cos 70° = 0.342 that (−70°) cos c sin = and = , sf), find sin b cos Given sin d find sinA = 0.8 cosA = 0.6, find each − A) b cos (−A) c cos (360° d sin (180° + A) e tan A f tan (−A) g sin (360° − A) h tan (180° terms that of a tan θ e sin (π a + sinθ and θ) = a and cosθ = b, value. sin (180° + cos a Given 290° value. d and each sin c that 250° 4 3 cos 3 (to Questions Given a and value. sin 110° Exam-Style 2 0.940 − A) A) find each value in b b sin (π f cos (−θ) − θ) c cos (π g sin (2π + θ) − θ) d tan (π + θ) h cos (θ − π) Chapter . Solving equations using the uni t circle Suppose we want to solve an equation such as sinx = . We know that sin 30° , = but we also know that sin 150° , = sin = , and = sin . So what is the value of x in the equation sinx = ? In x, fact, so there we looking need for. ● Is ● What x are an more We the number information need measured is infinite in to know degrees about two or of values the we values could of x substitute that we are things: radians? domain? Now suppose we want to solve the equation sinx = , for −360° ≤ x ≤ for which sinx 360°. There are two positions on the unit circle = , so we will find the angles at those positions which are within our 150° x = −360° ≤ x ≤ 360°. 30° –210° The domain –330° equation −330°, has four −210°, Example solutions 30°, within the given domain. 150° 2 Solve the equation cos x = , –2π ≤ x ≤ 2π 2 Answer 3r You –5r know 3 = 4 Draw other –3r 5r 4 4 this a position you the within 5 = , 4 3 Circular 3 , 4 functions 5 , 4 4 ver tical same Once on x . 2 4 4 2 cos on cosine have unit the ter minal line the unit found find circle both find domain at help the with value. circle, sides to all that these positions the have angles their positions. for Example Solve the equation tan x = 3, 0 ≤ x ≤ 720° Answer 60° tan 60° 3 = 420° Draw find a line the circle You through other with can this find the position same the origin on the tangent angles to unit value. 420° and 240° 600° 600° by around x = 60°, 240°, Exercise ✗ Solve 1 420°, unit another 600° equation for −360° ≤ x ≤ 360°. = cos x b = c tan x f tan = 1 2 sin x d = 0 cos e 2 x = x = Solve 2 each equation for −2π θ ≤ 2π ≤ sinθ a rotation circle. C each sin x a making the = b tanθ e 2tan = 0 c cosθ f sinθ = 2 sinθ d = −1 θ = 6 cosθ = Although Solve 3 each equation for −180° ≤ θ ≤ 720°. number 2 cosθ a = 1 b sinθ been the itself had studied for = 2 centuries, the use 2 sinθ c = −cosθ d 3tan x − 1 = 8 of the π symbol introduced Solve 4 each equation for −π ≤ x ≤ sin x = 1 b 2sin x 2 10 c sin Example + 3 = = 5 d 4cos Jones by (Welsh, 2 1675–1749). 2 x 1706 π William a in was x + 2 = 5 2 Solve the equation sin(2x) = , 0° ≤ x ≤ 360°. 2 Answer If 0° ≤ x ≤ 360°, then 0° ≤ 2x ≤ 720° We know that 2 135° sin45° 45° = sin135° = 2 495° 405° To find another unit 2x x = = 45°, 135°, 22.5°, 405°, 67.5°, 495° 202.5°, 247.5° the other rotation angles, around make the circle. These angles of not 2x, represent the value of the value x. Chapter Example 2 Solve the equation 2sin x + 5sinx − 3 = 0, 0 ≤ is a x 2π ≤ Answers 2 2sin x + (2sin x 5sin x − − 1)(sin x 3 = + 0 3) This = Solve 0 by ‘quadratic-type’ equation. factorizing. 1 sin x = or sin x = The −3 2 −1, can cannot disregard be less sinx = than –3. 6 Exercise 1 we sine , = 6 ✗ so of 5 x value Solve D each equation for −180° ≤ x ≤ 180°. a cos (2x) = b 6sin (2x) d sin − 2 = 1 c sin − Solve each 2 = 2 cos 0 equation for −π ≤ θ ≤ 2 = 3cos π a sin (2θ) = b tan (3θ) d sin = 1 2 c 2 = Solve each = 2cos QUESTION equation for 0 ≤ θ ≤ 2π 2 x − 5cos x − 3 = 0 2sin b 2 c tan . In this x + 3sin x + 1 = 0 2 x + 2tan x + 1 = 0 section, Y ou we will are look already equation identity , is an sin x = 6sin x − 5 identi ties at special familiar 2 trigonometric sin d Trigonometric identi ties. This 2 a 1 EXAM-STYLE 3 cos kinds with of one equations called impor tant 2 x identity , + cos x = because 1. it is tr ue for ALL values of x. Another identity with which you are familiar is tanx = , definition Circular of tangent, functions which is also tr ue for ever y value of x the Double-angle The diagram identity shows the for cosine θ −θ angles and drawn in standard position B(cos i, sin i) 1 in the unit circle. i i The length of segment CD is equal to the length of segment BD, 1 and we have BC We can found BD = see BD that using = the AB = 1 we put [1] 2θ. r ule The in [1] length of segment BC can be ΔABC: AC 2(AB)(AC)cos(2θ) − 1 2(1)(1)cos(2θ) − = 2 − cos(2θ) 2 two and 2sinθ 2sinθ. BC = 2 + have C(cos (–i), sin (–i)) 2 + 2 BC = so = cosine = 2 If CD, 2 BC we + sinθ = ∠BAC 2 BC Now CD = [2] expressions for [2] equal, we . BC find 2 Squaring both sides gives us θ 4sin = 2 2cos(2θ). − 2 Rearranging this equation gives us 2cos(2θ) = 2 − 4sin θ. 2 Finally , ➔ we The for divide by We will We know values use this cos(2θ) get = 1 − identity + 1 2sin2θ to help us 2 θ = − is 2sin an θ identi ty, as it is tr ue θ of 2 sin to cos(2θ) equation all 2 other 2 θ cos find = 1, so 2 θ = 1 = 1 − sin identities. − cos θ. 2 Using substitution, Rearranging this we cos(2θ) get equation gives 2(1 − cos θ). us 2 cos(2θ) = θ 2cos − 1. 2 We can substitute sin 2 θ + 2 2cos(2θ) = 2 cos θ − (sin The ➔ three The = = cos equations 1 into this equation to get 2 θ + 2 cos(2θ) θ cos 2 cos θ), which gives us 2 θ − we double-angle sin have θ just identi ties found for are: cosine: 2 cos(2θ ) = 1 − 2sin θ 2 = 2cos θ − 2 = cos θ 1 2 − sin θ Chapter Double-angle Now we will identity find a double-angle 2 We know that + From the identity (2θ) cos 2 for sine. = 1, so 2 (2θ) cos sine 2 (2θ) sin for = 1 − (2θ). sin double-angle [1] identity for cosine, 2 cos(2θ) = 1 − θ 2sin 2 2 cos (2θ) 1 sin = (1 − 2 θ) 2sin [2] 2 − 2 (2θ) = (1 − 2sin 2 θ) Equate 2 1 − 2 (2θ) sin = 2 − 4sin − 2 4sin The sin cosθ = θ sin (2θ) = sin 2 1 (2θ) sin − sin θ 2 = cos θ (2θ) sin(2θ) = double-angle Example 4sin 2 θ cos + 2 θ) 2 θ 2sinθ ➔ = 2 θ (1 [2] 4 θ 4sin and 2 θ 2 4sin − 4 θ 4sin 1 [1] identity for sine sin(2θ) is = 2sinθ T ake square both sides roots of cosθ 3 Given that sinx = , and 0° < x < 90°, find the exact values of 4 a cos x b sin(2x) c cos(2x) d tan(2x). Answers 2 a sin 2 x + cos x = 1 Pythagorean identity. 2 3 2 + cos x = Substitute 1 the value of sin x. 4 9 7 2 cos x = 1 − = 16 Remember , 16 7 cos x an 7 = Take the square root acute cosine 16 must positive. sin(2x) = sin(2x) = 2sin x ⎛ 3 ⎜ ⎝ ⎟ 4 3 sin(2x) ⎞ ⎠ cos x ⎛ 7 ⎜ identity. ⎞ ⎟ ⎜ Double-angle Substitute the value of sin x and ⎟ 4 ⎝ ⎠ cos x. 7 = 8 { Circular functions x is of 4 b if angle, Continued on next page be the Y ou 2 c cos(2x) = 1 − 2sin Use x a double-angle could use any of identity. the three identities for 2 ⎛ cos(2x) = 1 3 9 ⎞ 2 − ⎜ ⎝ = ⎟ 4 1 Substitute − the value of cos(2x). sin x. 8 ⎠ 1 cos(2x) = 8 2x sin d tan(2x) Definition = cos ⎛ of tangent. 2x 3 7 ⎜ ⎞ ⎟ ⎜ ⎟ 8 ⎝ tan(2x) ⎠ Substitute = the values of sin (2x) and 1 ⎞ ⎛ cos (2x). ⎜ ⎟ 8 ⎝ ⎛ = 3 ⎠ ⎞ 7 ⎜ ⎟ ⎜ ⎟ 8 ⎝ tan(2x) Example ⎠ = 3 8 ⎞ ⎛ ⎜ ⎟ 1 ⎝ ⎠ 7 4 Given cosθ that = 3 , and 5 a sinθ < θ < 2π, find the exact values of 2 cos(2θ). b Answers 2 a sin 2 θ + θ cos = 1 Pythagorean identity. 2 ⎛ 4 ⎞ 2 sin θ + ⎜ ⎝ = ⎟ 5 1 Substitute the value of cosθ ⎠ Remember , 16 9 3 2 sin θ = 1 − if < = θ < 2π, the 2 25 25 angle 3 sinθ 9 = Take the square root will four th be in the quadrant. The of 5 25 cosine the is sine positive is but negative. 2 b cos(2θ) = cos(2θ) = 2cos θ − 1 Use a double-angle identity. 2 ⎛ 4 32 ⎞ 1 ⎜ ⎝ 1 = Substitute the value of cos θ ⎟ 5 25 ⎠ 7 cos(2θ) = 25 Notice that, cos (2θ) in Example without ever 8, we finding could the find measure the of values the of sin θ and angle θ Chapter Exercise E Exam-Style Questions Given 1 that sinθ = , and 0° < θ < 90°, find the exact Y ou value of answer each. sin(2θ) a should cos(2θ) b of questions tan(2θ) c all nding be able these without the size of the Given 2 that cosx = , and 90° < x < 180°, find each value. angle. sin(2x) a cos(2x) b tan(2x) c Given 3 that cosθ = , and 0 θ < π, < find each value. tan θ a sin(2θ) b cos(2θ) c d tan(2θ) each value. Given 4 that sinx = , and 180° < x < 270°, find sin(2x) a cos(2x) b Exam-Style tan(2x) c d sin(4x) Question Given 5 that tanθ = , and 0 < θ < π, find each value. sin θ a cos θ b Given 6 that sin(2x) = , and cos(2x) x < tan(2x) b d cos(2θ) < a sin(2θ) c , find each value. c sin(4x) d cos(4x) Given 7 that tanx = , and 0° < x < 90°, find each value in terms of a b sin x a Y ou and can cos x b also Example use identities c when sin(2x) working with d cos(2x) equations. There Solve the equation sin (2x) = sin x for 0° ≤ x ≤ are more 360°. trigonometric Do not use your GDC. identities. are Answer they? identities sin(2x) = 2(sinx)(cosx) What What are used sinx in = sinx Use double-angle = 0 Rear range. = 0 Factorize. other areas identity. mathematics? 2(sinx)(cosx) − (sinx)(2cosx sinx = 0 If sinx = If 2cosx or sinx − 2cosx 0, then x 1) − 1 = 0°, = 0 180°, 360° 1 so x x = = − 60°, 0°, 1 0, then cosx = 300° 60°, Circular = 180°, functions 300°, 360° , to of Example 2 Prove that (1 + tan 2 x) cos (2x) = 1 − tan x Answer 2 (1 + 2 x) tan × cos(2x) = 1 − tan x 2 ⎛ 2 sin ⎞ x sin x 2 ⎜ 1+ ⎟ 2 cos ⎝ x ( 2cos x − 1 ) = 1 − Rewrite ⎠ − 1 + 2sin x sin = x 1 − Multiply x cos of the the left equation. 2 x + 2sin 2 = x 2 Simplify. 2 x + cos x Example for on x side 2 through 2 cos In cos x. 2 x − 2 sin and 2 x cos sin x x 2 sin 2 cos using 2 cos all of x 1 10, values values = we of and Divide x. is ended up with Therefore, also an the a known original identity , by 2. identity , equation though it is not which is tr ue one is tr ue for you all must lear n. When you ‘proving show Solve a to be tr ue in this way , it is called identities’. Exercise 1 equations F each sin (2x) equation = for 0° ≤ x ≤ 180°. cos x sin (2x) b = cos (2x) 2 c (sin x + 2 cos x) = 0 cos d x = 2 Solve each equation for −180° ≤ θ ≤ 180° 2 a 2sinx cosx = b sinx(1 − d cos(2x) b 2cos d sin(4x) b sinx sinx) = cos x 2 c cos 2 x = + sin x = sinx 3 Solve each equation for 0 ≤ x ≤ π 2 a tanx = sinx c cos(2x) x − 1 = 4 Solve = each cosx equation for 0 ≤ θ ≤ = sin(2x) π 2 a (sin(2x) + cos(2x)) 2 = 2 2 c 5 cos x Prove − 1 = = 1 cos x 2 = cos(2x) each 2sin d x identity . 2 a (sinx + cosx) = 1 + sin(2x) b ( ) = c 4 e cos d 4 x − sin x = cos(2x) Chapter Exam-Style The 6 Questions expression Find the value 2sin 3x of cos 3x can be written in the form sin kx. k 2 The 7 expression Find . In the value sections, relationships tangent y = to help Y ou in y with and = we have section, tanx. know written in the form 1 − bsin 2 x cos x. Y ou GDC to functions used different understand the be circular this cosine already the you and functions In can b between values. cosx, Sine of Graphing previous used cos 4x the angles you the unit and will circle their see will also help you practice solve find sine, how trigonometric to cosine these and values functions y graphing = can be sinx, these equations. functions the exact sine values for many angles, as seen table. Angle measure degrees, (x) radians Sine value (sinx) Angle measure degrees, (x) Sine radians (sinx) 1 7 0°, 0 radians 210°, 0 2 6 1 1 2 3 3 2 3 3 60°, −1 270°, 3 − 2 4 2 2 = 2 240°, = 4 2 − 4 2 45°, 1 5 225° 30°, 6 value 2 2 3 5 90°, 1 2 300°, 2 3 3 2 7π 315°, 120°, 3 3 1 4 2 5 Circular 1 6 2 1 π functions 2 0 2π − 2 2 11 360°, 6 2 = 330°, 2 2 150°, 180°, 4 = 135°, 1 − 2 0 If we let y = sin x, we can plot these values as coordinates on a graph. y 1.0 0.5 0 x° 90 180 270 360 450 540 –0.5 –1.0 “ Graphing same set the of equation axes, we y see = sinx on this “ this: If we measure graph has y the x in radians, same the shape. y 1.0 1.0 .5 .5 x° –90 We can same see sine Similarly , along “ y that the values if with = x 90 cosx, we the graph that let y = graph with x we of cosx, of the measured the found in we function y using can the plot function y = degrees: = unit the r r 3r 2 2 2 sinx is generating 5r 3r 2 the circle. cosine values we know , cosx “ y = y cosx, with x measured in radians: y 1.0 1.0 .5 .5 0 r x x 0 r r 2 2 –.5 –.5 –1.0 –1.0 r 2 2r 5 3r 2 Chapter ➔ If we compare the sine are the and cosine functions, we see many similarities. y ● The cur ves horizontal sa m e positions on size the and a xes shape, d iffer. only T he the ir s ine y = cos x c ur ve x 0 passes through the o rig in passes through the po int ( 0, ( 0, 0) , and the c o sine cu r ve 1). y ● The the functions same are cycle of periodic, values which over means and over. that they repeat The period, y = sin x or x length look of at apart, one two the cycle, points is 360° or 2π. This means whose x-coordinates y-coordinates of those two are that 360° points if 2π) (or would you be the same. ● Both functions minimum an this y is value ampli tude between = the case) −1, have of a −1. 1. Each The case). the or We ver tical of value these amplitude axis maximum this one-half maximum horizontal to in of a of is the also distance the wave say from 1 and functions minimum can of has difference (y = value that a a 0, (y the in = 1 or amplitude maximum to a minimum. We can use equations, earlier in the graphs much as we this chapter. the equation of y = used sin x the and unit y = cos x circle to to help help us us solve to Consider sinx , = −360° ≤ x ≤ 360°. By graphing a horizontal line y = on the same set of axes as sin x = y = sin x, we can see that there y y = sin x 1 y 1 = 2 x These x = points −330°, Circular correspond −210°, functions 30°, to the 150°. values are four points solve equations where Example The Solve the equation cosθ = 0.4, −360° ≤ θ ≤ GDC helpful Give your answers to the nearest can be ver y 360°. in solving tenth. equations and Answer T o with cosine change sine functions. to degree mode and choose Status 5:Settings | 2:Settings 2:Graphs Use & the to Angle and and GDC then select select to help and GDCs Enter y = set y 0.4 an view There is four −293.6°, −66.4°, 66.4°, GDC, on CD: four within | Casio are on Alternative for the TI-84 FX-9860GII the CD. and window Be sure DEGREE to your mode! intersection this solutions. these = graph. in to and the equation Graph θ into are points the cos x appropriate the GDC so = return document. demonstrations Plus to Graphing 4:Current the | Geometr y key move & domain, will Use have 6:Analyze 4:Intersection intersection to find points. 293.6° Chapter Example Angle Solve the equation sinx = 0.25x − 0.3, −2π ≤ x measures are in 2π. ≤ radians Give your answers to three significant figures. Answer GDC help on CD: demonstrations Plus and GDCs T o Casio are on mode | = sinx the = 0.25x − and to sure 0.3 into the the three = −2.15, Circular −0.416, functions 2.75 window is mode! intersection points domain, equation will have solutions. Use 6:Analyze Graph these GDC three this | 4: to select Press then select Intersection intersection to points. to return GDC, graph. your are within x the | and appropriate RADIAN There so an view Be in set & Geometr y key Angle the and and Graphing 4:Current y & to and y radian 2:Settings move Radian. Enter to 5:Settings 2:Graphs Use TI-84 CD. press choose Status the FX-9860GII the change Alternative for find document. to Exercise In G questions Give your 1 to 4, answers use to your the GDC nearest to solve each equation. each equation. degree. sin x 1 = , −360° ≤ x ≤ 360° 2 cos θ 3 sin θ 4 sin x = = , ≤ θ θ ≤ 360° −0.9, = cos(x In questions Give −180° your 5 0° − to ≤ 20), 8, answers 0° use to ≤ ≤ 360° x ≤ your three 540° GDC to solve significant figures. sin θ 5 = −2π , ≤ x ≤ 2π 1 cos θ 6 = , −π ≤ x ≤ 2π 2 e 7 cos x 8 sin x = −π −x, ≤ x 2π ≤ 2 = x Tangent − 1 , −2π ≤ the cosx Now 1 sine that tr y List 0°, a 3 On a 2π cosine already similar ±45°, 315°, graphing functions, values ±60°, 330°, of we grid the function for the angles: 120°, 135°, plot angle (measured value of values Connect y there = for sinx and = tanx 180°, 210°, 225°, 240°, values sometimes not points in values as degrees), points. and let Let the the x-axis y-axis tanx. tangent you do values for the angles have on paper to the ±90° graph or of a 270°? function exist? on your grid sketch the graph of tanx. Graph your Are that the no do y 150°, these the feature with 360°. paper , the are began to represent Why tan x knew. approach tangent piece – represent for 5 we the What 4 and ±30°, 300°, 2 ≤ function Investigation For x the function y = tanx on your GDC, and compare it to sketch. your graphs similar? Chapter If you had tangent been using function radians, would look rather like than degrees, the graph of the this: y 3 2 1 x 3r r 2 r r 3r 2 2 2 r –2 –3 ➔ Like the sine periodic. the The the sine an Example Solve the of and the functions, ver tical not pair of exist. cosine The has same no tangent at function values cycle of of x values is where repeats asymptotes. function functions, It the asymptotes ver tical tangent amplitude. the is 180° tangent maximum (or π radians). function or does minimum Unlike not values. equation your cosine are does each period have Give There function between and answers tanθ to = 1 three − x , −2π significant ≤ θ ≤ 2 π. figures. Answer Be sure your RADIAN There are within this equation GDC five have on CD: demonstrations Plus and GDCs θ = −4.88, Circular −1.90, functions 0.480, 2.25, 4.96 Casio are on is intersection domain, will help GDC in mode! so five the solutions. Alternative for the TI-84 FX-9860GII the points CD. Exercise In questions Give your 1 tan x 2 tan θ = 3 tan θ = 4 tan x In H = = 1 your 4, answers 2, , ≤ cos x, 0° 0° to ≤ 8, answers x 360° ≤ θ ≤ x ≤ ≤ use to GDC nearest θ ≤ your the −180° −1.5, 5 use to −360° questions Give to ≤ to solve each equation. each equation. degree. 360° 360° 720° your three GDC to solve significant figures. tan θ 5 = −2π , ≤ x 2π ≤ 6 tan θ 7 tan x = 2x 8 tan x = 4 = π, −π − ≤ 3, θ 0 π ≤ ≤ x 2π ≤ 2 . − x , −2π ≤ x ≤ Translations 2π and trigonometric Investigation – stretches of functions transformations of sinx and cosx Using your GDC and y = cos do you What do they Describe Now, mode, the same notice have the this and about in graphs are = sin x for sin x 2 y = cos x and y = 2 cos x 3 y = cos x and y = cos (2x) 4 y = sin x + = cos x axes. and y = sin = cos each these two functions? these tr y to pairs explain of why this is happening. functions. x of and 3 y of different, x and graphs 3 sin x y common? process y the = = functions y y the 1 5 graph 2 how repeat radian on x What in 2 Chapter In the last section, we looked at the basic trigonometric functions Y ou y = sin x, y = cos x and y = tan x. Now we will study need familiar of these functions. begin by looking at the graphs of the sine and be with features sine Let’s to ver y transformations cosine and of the the basic cosine functions, cur ves. and reviewing some vocabular y relating to these functions. y y 1 y = y sin x r 2 2 These the functions functions These graphs that you of have have these a Chapter rather an 2π of period than ampli tude functions transformed see –2 r 3 the can graphs (or r 2 360°, if we –1 r r 2 were 2r 2 graphing radians). of be of x r 2 degrees functions The book; in 3r cos x 0 x 3r = 1. transformed other in functions the same earlier in way this 1. Translations ➔ The function standard y sine The cur ve The function = sin(x) + d is a vertical translation of the cur ve. shifts up if d is positive, down if d is negative. A standard positive, It is “ or This left the graph = cosine impor tant period y to if c sin(x cur ve. is note a c) is The a horizontal cur ve shifts to translation the right if of c the that of vertical known shift’. a translation a trigonometric translation. horizontal translation is negative. amplitude shows − does “ not change the function. This graph shows a horizontal translation. The 2 sine units. cur ve The has green been shifted arrow shows up The of the cur ve has been shifted units 2 the the direction sine right. The green arrow shows translation. direction of the translation. y r y 3 = sin x y y = sin ( x – ) 2 y = sin x + 2 1 2 1 x r y = x r r 2 Circular functions r 3r r 2 sin x r r 3 r the to as is a also ‘phase ➔ The function standard cur ve The function positive, As or with the “ the The y sine if graph shows cur ve 3 units. is d is is a vertical − positive, c) is The a a down if cur ve shifts to d is direction of the cosine been green the negative. of translation the right does not if c the is the period function. translation. “ The shifted arrow change graph below translation. The shows cosine a horizontal cur ve has been 3 shows shifted the of translation horizontal translation vertical has The + negative. the a d cur ve. c of if cos(x cur ve, cosine down up = cosine left cos(x) cur ve. shifts amplitude This = cosine The standard y units translation. to the left. 4 3r y y y y = r 2 r r 2 –1 = cos x ( + ) 4 0 x r y cos x cos x 0 r = r 2r r 2 2 y = cos x – x r r r r 2 –1 3 –3 –4 Now consider the graph of the tangent function. y 3 2 1 x 3r r r r 2 2 2 3r r 2r 2 –2 –3 Remember amplitude, that this because function there are has no a period of maximum There are ver tical asymptotes at x = (or at x = ±90°, x = ±270°, or (or 180°). minimum It has no points. π , etc. etc). Chapter As with the sine translations We can = tan(x in − Sketch the the c) Example On and not combine equations y do + cosine change horizontal form y = functions, the period and sin(x y = the ver tical − c) + d, and horizontal tangent function. translations y = cos(x − by c) looking + d, at and d the graph same set of of y = sinx. axes, sketch the sinx + 1 y b = sin graph of: 2π ⎞ ⎛ a ver tical of c 3 ⎝ 2π ⎞ ⎛ x ⎜ y = sin + x ⎟ ⎜ ⎠ ⎝ 1 ⎟ 3 ⎠ Answers a y = sinx + 1 y The 2 basic function 1 unit sine is cur ve shown in is shown in blue. This red, is a the translated ver tical shift of upward. 1 x 3r r 2 2 y = sin 3r r 2π ⎞ ⎛ b r x ⎜ ⎟ 3 ⎝ ⎠ y Again, the basic sine cur ve is shown in red, the new 2 function is shown in blue. This is a horizontal shift 2 1 of units to the right. 3 x 4r 3 r r 3 r 3 3 3 r r 3 r 3 5 3 –2 2π ⎞ ⎛ c y = x sin + ⎜ 1 ⎟ 3 ⎝ ⎠ This is a combination of the translations from par ts y a and b, with the new function shown in blue. 2 The 1 basic units 3 x 5r 4r 3 3 r r r 2r 3 3 r r 5 –1 3 3 –2 Circular functions sine cur ve (shown in red) has 2 3 3 r to the right, and 1 unit up. been shifted Example Write a an equation Write a sine for each function, as directed. equation. y 0 –2r 3r r x r r r 3r –1 2 2r 2 –2 b Write a cosine equation. y 0 –2 c x r r 2 Write –1 2 one sine 3r 2 and one 2r 2 cosine equation. y 1 0.5 r –2r 5r 4r 3 3 r 0 2r x r 2r 3 3 r 4r 5r 3 3 2r 3 3 –0.5 –1 Answers a y = sinx − 2 You a can see minimum shifted b y = cos x is value value down 2 of a sine of cur ve −1 –3. It and has with a been units. + 4 this maximum You can see this is a cosine cur ve which has been shifted to the left by 4 c y = cos x + 0.5 3 You can see this as a cosine cur ve Because which has been shifted to the right of or , and up = sin sine there might also view this as a are and may so cosine be similar , many sine + 0.5 the cur ves You x shapes 0.5. 3 y the by 6 correct cur ve which has been shifted to equations for the the left by , and up graph of a sine or 0.5. 6 cosine function. Chapter Exercise For for I questions –2π ≤ 1 to x ≤ 2π. − 5 1 y = sinx 3 y = tan 8, sketch the graph of the function 2 y = cosx 4 y = sin 2 + 5 y = cos y 6 = sin = cos − 1.5 y 8 = tan For questions 9 to 12, write an equation y 1 0 x r r 2r r 2r y 3 2 1 x –2r r 0 y 6 4 2 0 3r r 2 2 x r 3r 2 2 2r –2 y 0 –2 3r r –1 –2 –3 Circular functions x r 2 r 3r 2 2r for the 2 + –2 − y 7 4 function shown. Vertical ➔ The stretches functions vertical When the = asin x of stretches the stretch, y g raph ever y value of of and the a y-value y sine the acos x and func tion in = are cosine func tio ns. und ergoe s original a function ver tic al is multiplied by y = asin a. x 0 If |a| > 1, the function will appear to stretch away from the x-axis. If 0 the y <|a| x y <1, the function will appear to compress closer = sin x |a|>1 to x-axis. y If a is negative, the function will also be reflected over the y = sin x x-axis. With a In by stretch, function will change function will not the a ver tical graph factor minimum function below , of 3. is are from of ampli tude 1 to |a|. The the sine period or of cosine 0 x y the = asin x |a|<1 change. the The values the sine cur ve maximum at y = −3. has been values The are stretched at y amplitude = of 3, ver tically and the the new 3. y 3 2 y y sin x = = 3 sin x 1 x –2 3r r 2 2 3r r –3 The the next been The are graph x-axis. shows of multiplied maximum at The All y = the by a ver tical y-values in stretch the that is standard also a cosine reflection cur ve about have −0.5. values are at y = 0.5, and the minimum values −0.5 amplitude of the new function is 0.5. y y = cos x y = –0.5cos x 0 3r 2 r x r r 2 2 r r 2 –1 Chapter Example Sketch On a the the y graph same = set of of y = cosx. axes, 0.25cosx sketch y b = the graph of: −2cosx Answers a y = 0.25cosx y The basic cosine cur ve is shown in blue, the new 1.0 function stretch is shown factor in red. This is a ver tical stretch of 0.25. x 3 r r 2 r 2 –1.0 b y = −2cosx Again, y new the basic function is cosine shown cur ve in is shown in blue, the red. 2 Ever y y-value multiplied r r 2 2 Horizontal ➔ The the to blue give function the red has been function. 2r 2 2 stretches functions horizontal When in −2 x 0 –2r by the y = sin(bx), stretches graph of of a y the = cos(bx) sine, function and cosine y = and undergoes a tan(bx) tangent represent functions. horizontal stretch, ever y x-value in the original function is multiplied . by We could divided also by that ever y x-value in the original function is b Multiplying changes say (or the dividing) period of a the x-values by trigonometric a number in this way function. y y ● If |b| > 1, the period will be shor ter, and the function = sin b x y = sin x will x appear ● If 0 < will ● If b to compress |b| <1, appear is to the toward period stretch negative, the the will away y-axis. be from function will longer, and the function |b|>1 the y-axis. also be reflected over the y-axis. y When a sine or cosine function undergoes a horizontal y = sinb y = sin x stretch, the period of the function from 360° to Circular functions will change from 2π to , x or x |b|<1 “ In the blue graph has a below, period the sine cur ve in “ π of In the in blue graph has function y y = sin below, a period has also the of been sine 4π. cur ve The reected (2x) about 1.0 the y-axis. y 0.5 y = sin (–0.5x) y = sin x 1 x 3 –2r r 2 3 2 2 r 2 x –3 y ➔ For a function in the = r r 3 sin x form y = tan (bx), the period will y change from π to , or from 180° to 4 The graph to The period the of right this shows function is the function y = 2 tan(0.5x). 2π x –3r Example r r r r 3r –4 Sketch the graph of: y = sin (0.5x) a b y = tan (2x) c y = 2 cos (3x) Answers 2 y a = The sin(0.5x) period of this function is , or 0.5 y 4π 1 x –3r –2 r r 2 3r 4r y b = The tan (2x) period of this function is 2 y 4 2 x r r r 2 3r r 2 2r 2 –2 –4 2 c y = The period of this The amplitude function is . 2 cos (3x) 3 is 2. y 2 r 0 r 2r x Chapter Exercise For J questions 1 to 8, sketch the graph of the function from –2π ≤ x ≤ 2π. y 1 = 0.5 sin x y 2 = −4 cos x y 3 = tan y 4 = sin (–2x) y 5 = 2 cos = −2.5 sin (0.5x) y 8 = questions 9 to 12, write an equation for the function shown. y y 3 sin (3x) For = −cos y 6 y 7 8 7 6 5 0 –6 4 –4r r x 2 4r 6r –1 3 2 1 0 r x 2 –1 3r –2 –3 –4 –5 –8 y y 6 3 2 4 1 x 0 –2r 2 2r –1 3r x –6r –4r –2r 2r 4r 6r –2 –4 –6 . Combined and In y this = For cosine section, asin(b(x − functions transformations we c)) of will + d this wi th sine functions be and looking y type, = at functions acos(b(x there are − four c)) + of the form d possible transformations happening: ● a represents cosine ● b a represents function. a to Circular functions will stretch. be period The equal horizontal The equal ver tical function of to stretch, the amplitude of the sine or |a|. which sine or affects cosine the period function will of be the ● c represents shift ● d to a the represents up if d is horizontal right a if c is ver tical positive translation, positive translation, or down The function y = 2 sin same axes as the basic sine if d or to or is shift. the left shift. The if The c function is will negative. functions shifts negative. or is shown in blue on the cur ve (shown in red). 3 2 1 x 3 This function function y function in two ● = sinx blue. changes There has to has ● been There amplitude has the of have a 1. been 2 and four been a period 4π. of transformations two changes to The to become the y-values the and x-values. ver tical All the multiplied has of undergone There been translation have an a stretch of y-values in by 2, then horizontal scale the factor standard increased stretch of 2 by scale and sine a ver tical function 1. factor 2 and a horizontal translation of . All the x-values in the original sine function have been multiplied by 2 (divided by ), then decreased by The function y = 3 cos is shown in blue on the y 3 same axes as the basic cosine cur ve (shown in red). 2 This function has an amplitude of 3 and a 1 period of π. undergone The four function y = cos x transformations to has become x 2r the ● function There All has the have in blue. been y-values been a –1 ver tical in the multiplied stretch standard by of scale cosine factor 3. function 3. ● There has been a horizontal stretch of scale factor , a reflection about the y-axis, and a horizontal translation of . All the x-values in the original cosine function have been divided by −2, then increased by When sketching step-by-step functions like these by hand, it is best to take a approach. Chapter Example 2 Sketch the graph of the function y = 5 cos 3 x + 2 Answers This a function ver tical The will shift of maximum function will have amplitude of 5 and −2. and be an 3 The y minimum and −7, values of = horizontal −2, which axis is of the the wave ver tical will be translation. the respectively . y 4 2 Mark these maximum and minimum values 1 0 –2r r (shown in red) and (shown in green). the axis of the wave x r –1 2r 3r –3 These will be helpful guidelines when –4 –5 graphing the function. –6 –8 2 Period = 2 = b = 2 This function horizontal 3 = 3 2 3 will shift 2 of have a period of 3π and a −π. y 4 2 1 The 0 –2r r x r –1 2r standard where 3r x = 0, maximum cosine so this where x cur ve has function a maximum will have a −π = –3 –4 As the 3π units period is 3 π, there will be another maximum –5 –6 to maximum the right, points where on the x red = 2π. Mark these line. –8 Use your knowledge of the features of the cosine y cur ve 4 and to the mark points other on points, the axis such of as the the minimum wave. 2 1 0 –2r r –1 x r 2r 3r Midway –3 there is a between two minimum maximum values, value. –4 –5 Midway between the maximum and minimum –6 values, –8 there (horizontal) will be points on Circular functions green axis. { the Continued on next page y Connect these points and sketch the function. 4 2 You 0 –2 may want to erase the guidelines when your x r r 2r 3r sketch is complete. –4 –6 –8 Example Find one the amplitude cosine and equation for period, the then function write one shown in sine the equation and diagram. y 2 1 0 –2 x r r 2 3r 4r –1 Answer 3 − The amplitude ( −1) is = 2 The amplitude is one-half the dif ference between the 2 maximum and the minimum value. 3 + ( −1) The ver tical shift is = 1 2 The period is 4π The period function to find is a this 5 1 = 2 sin x 2 horizontal one looking point point to to at a a distance c ycle. The the it takes easiest horizontal maximum minimum for way distance point or the to from from a point. + 1 + the by maximum minimum y is complete For a sine function, the horizontal translation the x-coordinate is 4 found the by looking horizontal gradient. This standard sine at axis of the wave, cor responds to the this a point a point on positive (0, 0) on the cur ve. In of with function, one such point is 5 ,1 , so the 4 5 horizontal translation is 4 { Continued on next Chapter page The y = 2 cos 1 x 4 and amplitude, + 1 + 2 sine cosine function have the same For a period, cosine translation maximum to the standard looking point (0, on 1), cosine point function, by point you at the can the translation. find cur ve. This is In the horizontal x-coordinate a this of a cor responds maximum function, on one the such 4 ver tical which cur ve. ,1 is and , so the horizontal translation is 4 Remember, that ➔ there can be For sine written and translations Exercise For for for be a cosine will more given than sine functions differ by write one one or of possible cosine the equation function. same one-fourth correct the cur ve, period the of horizontal the function. K questions the may 1 to 4, sine and one cosine equation function. y y 1 2 3 2 0 –3r –2r x r r 2r 1 0 –2r x r r 2r –2 –3 –4 –5 y y 3 4 5 4 3 3 2 2 1 1 0 –2r x r –1 –2 x –2 3 r r 2 For at 2 questions least one 5 full to10, Circular 2r –3 2 a neat sketch of the function make 7 2 3 over cycle. 5 r functions 6 8 2 3r 3r . Many Modeling real-life functions. average of situations Examples ➔ be used To to create to model a the amplitude ● the ver tical ● the horizontal ● the period. and sine to Example Create a modeled at using heights, section, how we sine cosine sine sunrise will and functions and times, use our cosine cosine and knowledge functions data. function of the model for data you need to know: function translation its left has the same horizontal of the amplitude, translation cosine ver tical is translation one-four th of the cur ve. model measured be and translation but the sine tide this look function period period In cosine ● The can include temperatures. transformations can wi th off a for this buoy data, in the which ocean shows over an the depth 18-hour of the period, water star ting at midnight. T ime 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 6.7 8.3 9.1 8.1 6.4 5.6 6.7 8.4 9.2 8.2 Water depth (m) Answer Enter and data depth), GDC. will The be depth the into on will lists then (label plot the independent the be x-axis, the these data time on the variable, and the dependent time, Be water variable sure your RADIANS GDC is in mode. on y-axis. From the graph, minimum which occurs maximum Use the value these at 5.6 metres, 10:00. The value values the is is to 9.2 metres. estimate amplitude. GDC help on CD: demonstrations Plus and GDCs { Continued on next Casio are on Alternative for the TI-84 FX-9860GII the CD. page Chapter The an data is clearly apparent Now To tr y to develop horizontal The find the a with trigonometric model, estimate translations amplitude and periodic, the water height rising and falling in patter n. minimum is of the one-half function the model amplitude, this period, data. and ver tical and function. the ver tical distance between the maximum values. 9.2 Estimated to amplitude 5.6 = = 1.8 metres 2 The vertical translation is the value half-way between the maximum and Y ou minimum can also nd the values. ver tical translation 9.2 + 5.6 Ver tical translation = by = 7.4 subtracting the 2 amplitude The period is the horizontal distance the function takes to from maximum one cycle. The maximum values are at 4:00 and 16:00, so estimate to be 12 the estimate data, points either the seem of these Substitute the easiest to have horizontal way is to for estimates the by a the To create maximum where x = 4 a cosine point. and The where model a the amplitude minimum value. for plotted x = 16. Use translation. equation y = a cos(b(x – c)) + d ⎞ ( ⎜ for point horizontal into 2π = 1.8cos translation. look maximum x-values these ⎛ y or hours. to Finally , value, the adding period a complete x − 4 ) + 7.4 . ⎟ 12 Enter axes this as equation the data into the GDC and graph the function on the same points. GDC help on CD: demonstrations Plus and GDCs Y ou are on – create you TI-84 CD. function it the FX-9860GII the could sine T ry Casio Alternative for a instead. should get 2 y The function appears to be a ver y good model for the = 1.8sin data. 12 Y ou could Circular tr y to functions make minor adjustments to get a ‘better fit’. + 7.4 x 1 Example The y a = following a cos (b(x set − of c)) + data can be modeled by the function d x 1 2 3 4 5 6 7 8 9 10 11 y 4 7.6 9.4 7.6 4 2.2 4 7.6 9.4 7.6 4 Use the data horizontal b Write c Graph d Use the the estimate function function regression data, the period, amplitude, and ver tical and translations. cosine the the to and on which the same function graph this on models axes your function on as the the GDC the data. data to get same points. a sine axes as model the for data points. Answers 9.4 a Amplitude 2.2 = = 3.6 2 9.4 + 2.2 Ver tical translation = 5.8 = 2 Horizontal Period = 9 translation − ⎛ b 3 6 + 5.8 ⎞ ( ⎜ 3 6 2 = 3.6cos ⎝ = = x 3) ⎟ Be sure your GDC is in ⎠ RADIAN mode! c Use the Sine Regression under the menu. the Be GDC contain function STAT sure which the CALC to tell lists data (x, y). d GDC help on CD: demonstrations Plus and GDCs Casio are on Alternative for the TI-84 FX-9860GII the CD. Chapter Exercise L What For each set of real situations data, modeled Use a the data to life estimate the period, amplitude, and can by ver tical functions? and horizontal what translations. adjustments Write b a cosine function in the form y = acos (b(x − c)) + model the Graph d Use the to be made data. to c function on the same axes as the data account for points. uctuations the might d need to be periodic regression function on your GDC to get a in the sine data? model as the for the data data, and graph this function on the same axes points. 1 x 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 y 11.8 8.5 2.2 5.5 11.8 8.5 2.2 5.5 11.8 8.5 2.2 x 5 10 15 20 25 30 35 40 45 50 55 y 12.5 9.3 12.5 18.9 21.9 18.9 12.5 9.3 12.5 18.9 21.9 x 2 4 6 8 10 12 14 16 18 20 22 y 1.8 2.1 1.8 1.3 0.7 0.5 0.7 1.3 1.8 2.1 1.8 When to you make have function (t ) be you can use that function Use this 8 ii 19 Use to function to height estimate of the a passenger height of a above the passenger boarding above the platform on the London Eye. platform boarding after function + 67.5 ⎟ ⎠ the after minutes this 15 ) 30 model minutes ⎞ (t ⎜ used i 2π = 67.5cos ⎝ b data, ⎛ a model function h can to predictions. Example The a to boarding. estimate how long it takes for a passenger to first reach a height of 100 m. Answers a i 8 minutes after boarding: ⎛ h (8) passenger is 30 t = 8 in the function. ⎞ (8 ⎜ ⎝ The 2π = 67.5cos Substitute − 15 ) + 67.5 ≈ 74.6 ⎟ ⎠ approximately 74.6 metres above the platform. { Circular functions Continued on next page 19 ii minutes after boarding: 2 p ⎛ h (19 ) = 67.5cos passenger is ≈ 112.7 + 67.5 ⎟ 30 ⎝ The ⎞ − 15 ) (19 ⎜ ⎠ approximately 112.7 metres above the platform. ⎛ b h (t ) ≈ 9.90 Exercise The depth + 67.5 = 100 Set the the height. function equal to 100, for ⎟ 30 ⎠ M depth by the 15 ) minutes EXAM-STYLE 1 ⎞ (t ⎜ ⎝ t 2π = 67.5cos QUESTIONS of the function of the water d (t ) water at the = 5.6sin in end ( metres, of a pier 0.5236 ( t and t is can − 2.5) the be estimated + 14.9 , where ) number of d hours is the after midnight. 2 a What b Estimate the depth of the water at midnight. c Estimate the depth of the water at 14:00. d At The is the what time average is the a the What is day What does c (1 How is it this the function? water first in a reach city its can highest be depth? modeled ( ) = ( ( − ) ) + , Jan = the of of temperature temperature year first b will high the function T period 1, in 14 degrees Jan expected = Celsius, 14, high and d is the by where day of etc,...) temperature in this city on the Febr uar y? the highest expected temperature, and on what day occur? many days each year are expected to remain below freezing? 3 A Ferris height wheel of 46 20 minutes a If a will b he Write t How d For 40 is a wheel the to the child of make for to boarding length park minimum Ferris riding function after high what amusement and on after sine minutes c the gets be a an metres for child at if time one the full of a 1 maximum metre. It takes rotation. when t = 0, how high minutes? model he height wheel 10 reaches the Ferris has will height the child wheel. been the of riding child be for 3 higher minutes? than metres? Chapter EXAM-STYLE 4 The owner discovers day of a QUESTION of of he sells January , Assuming Let x How of c ice a cream shop minimum and a of tracks 5 maximum his gallons of 37 annual of ice gallons sales cream on the and on first the first day July . function, b an the annual create represent many an the gallons sales can equation to be modeled model this by a cosine situation. month. would he expect to sell on the first day April? During what month would he expect to sell 30 gallons of Extension material Worksheet 13 - temperatures ice cream Review in one on CD: Modeling project day? exercise ✗ 1 Given find 2 cos 70° values a cos 110° b cos 250° c cos (−290°) Given find 3 that the that the sin 40° values a sin 140° b sin 320° c sin (−140°) Solve each = 0.342 (to three significant figures), of = 0.643 (to three significant figures), of equation for −360° ≤ x ≤ 360°. a b c EXAM-STYLE 4 Solve the QUESTIONS equation sin 2x +sin x = 0, for 0 ≤ x ≤ π The 5 The graph of f , for 0 ≤ x ≤ 9, is maximum shown. and a Given that the function can be written in the a has at a (6, minimum 11) at form (2, graph 1) ( ) = sin ( ( − ) ) + , y i find the ii explain values of a, c and d. 12 why 10 8 b Write down the inter val for which ( ) > 6 4 2 0 Circular functions 1 2 3 4 5 6 7 8 9 x 2 6 Given that cos x = , and x is an acute angle, find 5 a sin x tan b x sin c 2x 2 7 Sketch the graph of the function f x x −3 ≤ x ≤ Review 1 Solve a 2 Solve a = 0.75 The equation cosx of f , = −2π for cosx b 3 −180° ≤ x ≤ 360°. −0.63 ≤ θ c tanx c = = 3x − 1 ≤ x ≤ 7, is 0 for −2.8 2π ≤ cos graph for b 3 5. equation each 2sin 2, exercise each sinx 1 5 for 3cos shown. A(2, 7) 7 a Given that the function can be written in the form 6 f ( x ) = acos bx + c, 5 find b the Write values down of the a, b and solutions c. 4 to the equation 3 2 1 4 The depth of the water at the end of a fishing pier is given by 0 the function of the water in metres, x 1 , where D is the depth 2 –1 B(4, –1) and t is the number when the depth of hours after midnight. Low high tide tide Find b Sketch c At d the a what Fishing The at values graph time 8 is 4:00, 10:00, of P of the does when and of the of depth the of water the is water 6 m, is and 14 m. Q function the prohibited metres. longest day 15 hours 21 December, of h ( x ) = x How of with of water a Find b How 1 on the 1 D, first for 0 ≤ reach a t ≤ 24. height of many year 9.35 of the water hours in a city shor test hours of daylight depth each is day day is is 21 June, of the less fishing prohibited? with year is daylight. can ( x − ) + B, where be x modeled is the day by of the the function year Jan). value many when The hours A = the daylight. The number (i.e. at metres? than 5 occurs a 8 occurs of hours A and of of B daylight would you expect on 1 Feb? Chapter CHAPTER Using ● the The unit of unit. 1 will 13 unit circle meet SUMMARY The the circle has its center terminal unit side circle at at the of a origin point (0, 0) angle θ any with in and a radius standard coordinates length position (cosθ, sinθ). B(cos i, sin i) i A(1, 0) x 0 ● For any θ, angle , where cosθ ≠ 0. ● For any θ: angle ■ sinθ ■ cosθ = cos(−θ) ■ tanθ = tan(180 = sin(180 θ) − Trigonometric θ) + identi ties 2 ● The ● The for cos(2θ equation all values ) θ = 1 − 2sin is an identi ty, as it is tr ue θ of double-angle identity for cosine for sine are: 2 cos(2θ) = 1 − 2sin θ 2 θ − 1 = 2cos 2 = ● The cos double-angle Graphing ● The sine Both Like the There does ● of period of and amplitude. function sine cur ve. the have axes. graphs The maximum = 2 sin θ cos θ of the functions value of 1 same size are periodic and a and shape with minimum but period value of different 360° –1, and It y same at cycle the values of tangent of values x function Circular functions 2π. an where repeats the is periodic. function between each tangent functions, has = function no sin (x) cur ve the + d is a up 180° tangent maximum shifts is or d is radians). function minimum vertical if (or π does not have values. translation positive, Unlike down of if the d is standard negative. Continued or asymptotes. the The functions, asymptotes cosine The on cosine The ver tical sine sin (2θ ) functions functions a is 1. and exist. pair an ● not of have ver tical The the positions sine are θ identity cosine functions ampli tude sin circular and horizontal ● 2 θ − on next page ● The function standard left ● if The c The is cur ve. standard ● The of c) is = cos (x) The y = + cur ve cos (x c) y = asin x and a is will and to of translation the right if c is by from d is = acos x value to to the |a|. right vertical the y-value of down the positive, graph in the if the if translation are When c d of standard is negative. the is stretches of a function original a ampli tude 1 positive, shifts ever y the the if of translation horizontal functions. stretch, change vertical up a y stretch, multiplied of The the sine period or of cosine the function change. functions horizontal When cosine ver tical ver tical not shifts cur ve functions function horizontal a is The negative. sine is shifts − cur ve. d is a a cur ve c With The − The if the left function ● sin (x cur ve. cosine undergoes will y function positive, = negative. function cosine ● y cosine the y = sin (bx), stretches graph of a of y = the cos (bx) sine, function and cosine y and undergoes a = tan (bx) tangent represent functions. horizontal stretch, ever y x-value in the original function is multiplied by . ● When a stretch, sine the or cosine period of function the function 2π to undergoes will a horizontal change from , or from 360° to ● For a function in the form y = from π tan (bx), , or from 180° sine and translations Modeling ● ● To create a cosine will with cosine amplitude ■ the ver tical ■ the horizontal ■ the period. sine of the by and function the of the one-fourth sine of sine same the cur ve, period cosine model for data the of horizontal the function. functions you need to know: function translation function and period functions differ the translation wi th functions ■ The change to transformations cosine For will Combined ● period to and the to translation has the period the same but left of its amplitude, horizontal the cosine ver tical translation is one-four th cur ve. Chapter Theory of knowledge ‘pure’ and ‘applied’. areas? A a is t weigh as g, sprin the t weigh d pulle we sed, relea e oscillat up it h at t heigh by given is s second t t, weigh the of t heigh ion oscillat the down time and let g restin n Whe n. show is If on ded suspen will h(t) . down and t weigh The 5cm s. second b and e Ignor c)) d pulle full two s value the Find down one tes ever y of c the ion frict is comple and ion oscillat a, – (t (b sin a = ts eec air and of e. tanc resis s far ws as the of atics This question ignore the should will is an effects oscillate reduce example pure friction and air indefinitely . But in until of of the weight comes mathematics. resistance, real to life, the the If refer we , weight they n; oscillations are and rest. do What is the studying point pure problems like of Should mathematics applied this, which when we only study mathematics, could have reality.” some Albert the in Theory of results real are unrealistic practical life? knowledge: use? Einstein, Sidelights on Relativity Pure vs. applied mathematics There are 10 Pure mat without types of ha mathematic and solve people in this world: those who pr understand binary physics, econo and those who don't. Application Practical applications George Boole, an English mathematician, pure mathematics after the rst − ideas s developed 1850s. wer his This Boolean system Logic was system later used in in the digital electronics. Modern computers number system. use German In physics, elementar y par ticles were 3 Gottfried Wilhelm Leibniz discovered wrote about this number only 0s and 1s, in symmetr y he was studying this be used 300 “Physics not because physical it is we world, only its years Russell, of the the mathematics. all ‘pure’ mathematics will be used later . so much because we mathematical we elegance mathematical know but that Bertrand is or ‘p Perhaps would involving the underlying When arguments sy beauty, uses through can about know so the little; proper ties discover.” English mathematician and { philosopher (187 rge Boole 1970) 15–64) Pure ma entirely game new mathematical disciplines, such as statistics and theor y . Can we model the real world mathematics because we mathematics to the because the mirror world is with create world, What does this relationship or sciences, intrinsically tell us between about the mathematics the natural and the natural world? mathematical? Is mathematics invented or discovered? Chapter Calculus with trigonometric functions CHAPTER OBJECTIVES: 6.1 T angents 6.2 Derivative 6.3 and rule, Local maximum + b, integrals, of Kinematic distance Before Y ou 1 integral of Find the by rules, points, between and with a or boundar y between about the involving differentiation second points graphs cos x, inspection, areas problems of including condition cur ve Use f, f ′ and sum of inexion, to of these how value unit of displacement with form determine s, functions of the 1 linear constant areas cos v and acceleration the values. identities exact value of b in to cos 4 2 11 4 = 2x – – 1 2cos x + (2cos x – = cos – cos x for 0 ≤ x ≤ 3 2π. x = – cos 2 x Solve each cos x – 1)(cos x 1 = + 0 1) = 0 a 1 + b sin tan equation 2x x – = sin for c 1 or cos x sin x = cos x = 0 1 cos x + + 1 2 5 , , 3 3 Find the derivative 3 3 3 Use the product, quotient and chain a f (x) = 2x b f (x) = x c f (x ) x e r ules 2 to find ln(x derivatives. x 2 e.g. Find the derivative of f (x) = x ln x. 5 2 x 4 2 f (x) = ln x x ln x d 2 f ( x ) 1 (ln x )(2 x ) = Calculus with x x f (x ) = x trigonometric functions + 2x ln x x ) 0 ≤ x 2 x 2 total sin d tan 2 x a, solve 2 cos x cur ves, 3 7 2 x term, between 6 2cos function check Find c 2x functions, f (g(x))g ′(x)dx the x-axis, velocity Skills to: trigonometric circle trigonometric cos multiple, start know for Solve real x-axis equations. e.g. a f ″ the the and graphs composites and a 2 a derivative of substitution the of traveled exact functions quotient sin x equations including minimum revolution you should their tan x, relationship Anti-differentiation volumes 6.6 and and integration denite and cos x, product the Indenite ax 6.5 sin x, chain including 6.4 of normals, of cos x ≤ 2π At The Chocolate Califor nia, is driven bottom In the by of vat a the into the other in milk Ghirardelli chocolate that pushes is the Square, stirred blade San by back a Francisco, stirrer and blade forth which across the vat. stirrer, periodic mechanism. and of wheel chocolate translated the a Factor y One end the linear end of periodic the of motion a rod circular rod is is of the motion blade. attached attached to to the of The a the wheel diagram wheel or is shows wheel rod crankshaft i stirrer vat blade inside the vat. blade backwards As the wheel turns, the rod pushes the stirrer blade between the and center of forwards the wheel across and the the vat. stirrer The distance blade can be modeled d 2 by a function distance To find from in Many metres the the this: d (θ) like angle center real and θ of of world is 2cos θ + = the rotation the angle when wheel, you phenomena, of 25 rotation the blade would such as 4 sin heart of is use , where the the the d is wheel in shor test derivative rhythms, the radians. distance of d (θ). y movement tan x 2 of hands on a clock, the tides and circular motion, have periodic sin x behavior – they follow a pattern that recurs at regular intervals. x r cosine and tangent – which are periodic functions. Y ou can see 3r 2 r r r 2 2 r r r 2 cos x from In their this and graphs chapter tangent order to that you will functions investigate each find and the function’s values derivatives integrate behavior of of sine –2 recur. the and periodic sine, cosine cosine functions, functions like this in one. Chapter . In Derivatives Chapter constant 7 you real met of these trigonometric proper ties of functions derivatives, where c is a number. d Constant c rule: dx d Constant multiple [cf rule: ( x ) ( x ) ] cf dx d Sum or dierence [ f rule: (x ) ± g ( x )] = ′( x ) f g ′( x ) ± dx d Product [ rule: f ( x ) g ( x )] ( x ) g ( x ) f g(x ) f ( x ) , g(x ) dx d Quotient f (x ) g(x ) rule: ( x ) f f g ( x ) (x ) dx g(x ) 0 2 g ( x ) d Chain [ rule: ( g ( x ))] f ( g ( x )) g ( x ) f dx Investigation: Here the is the graph questions of The f (x) = derivative sin x for –2π ≤ x of ≤ sine 2π. below. Use it to answer f(x) The There 1 are four values of x in gradient horizontal f(x) –2π ≤ x 2π ≤ gradient of where the the tangent line a is 0. values of sin x = 1 line of 2 So at the to x where the tangent x 3r f (x) = sin x is equal to r r zero. r r 3r lines 2 What are these the 2 List values is that the are to is true decreasing, this plot and what sketch Use a GDC –2π ≤ x ≤ Compare the those to 2π. the the is of Be graph is sign the GDC is of of the plotted in derivative of in derivative f (x) = your against of When f ? 4 5 question Make a f (x) sin x. = Verify of your What with Adjust based function conjecture for chose Calculus 2. conjecture values you in in the your on drawing the do graph you numerically function question you think with graphed 4. trigonometric of f is f is When 0. = sin x increasing, f is derivative of to x f (x) question sin x radian on f graph decreasing. you of of the derivative derivative the derivative where the points your of it the about graph the sure of the 2π ≤ where the the graph x sign tr ue and ≤ of of 1 f ? to Use make a f in the inter val Enter mode. GDC to the one the functions if of is a in the GDC derivative derivative by of of sine? comparing question 3 (sin( x )) dx necessar y. the graph: d you f 1( x ) drew horizontal four graph –2π of about information possible 3 on inter vals increasing what are derivative equal points f they? –2 Use to 2 and the the table function d In the investigation, you should have found Y ou that (sin x ) Now consider the derivative of f (x) = cos can examine a cos x dx geometric x of this justication fact in the TOK section If you translate the graph of sine to the left , you get the cosine. So f (x ) cos x sin x the end of graph 2 of at this chapter . f(x) 2 2 f(x) = r 2 cos x f(x) = sin x 1 x 3r r r r 2 r r 2 –2 d Hence, d (cos x ) sin dx dx x Using d 2 cos x (1) 2 x rule: 2 2 x cos x d 2 cos x cos sin chain dx the x 2 2 dx 1 If you translate the graph of cosine to the left , you get a 2 reflection of the graph of sine in the x-axis. f(x) So r 2 f(x) f (x ) cos –sin x f(x) r r 2 d conclude that (cos x ) cos x consider the derivative s f (x ) tan x of f (x) = tan x. 2 We r r 2 2 sin x 2 r –1 dx Finally x 0 3r we cos x sin x 2 Therefore = x = –2 know that n x , where cos x ≠ 0. cos x d d (tan x ) So, ⎛ sin x ⎞ = ⎜ dx dx ⎝ ⎟ cos x ⎠ cos x (cos x ) − sin x ( − sin Apply x ) the quotient = 2 rule. (cos x ) 2 cos 2 + sin x = 2 cos x Use the identity 2 1 cos = , cos x ≠ 2 θ + sin θ = 1 to 0 2 cos ➔ Derivatives f (x) = sin f (x) = cos of x x simplify x sine, ⇒ ⇒ f cos ′(x) f ′(x) = and cos = – the numerator . tan: x sin x 1 f (x ) tan x f ( x ) , cos x 0 2 cos x Chapter Example In the 18th Find the derivative of each 17th and centuries the function. development of 1 a f (x) = sin x + cos x c y mechanical = devices tan x shifted 2 y b = cos(t the d f (x) = sin trigonometr y (2x) original Answers a f (x) f ′(x) sin = x cos + x cos – Take x sin the derivative of each ter m. = cos ( t periodic Joseph x Apply ) the chain rule, where outside 2 = [ − sin(t )] derivative of outside with u(t) = cos t motion. Fourier a mathematician and function re espect respect to inside function and 2 the derivative of is to modeling [2t ] function function its the French y′ to (1768–1830), 2 y b of from connection triangles = eld 3 ) inside function is v (t) = physicist, found t inside that with almost any to t periodic function, such the 2 = −2t sin( t ) Rewrite using rational vibration exponents. of 1 y c as a violin string or = the tan x movement of the 1 = ( tan x ) pendulum 2 y′ = 1 ⎛ Apply −1(tan x ) ⎜ ⎝ the chain rule, where could the be a clock, expressed as ⎟ 2 cos x ⎠ –1 outside 1 function is u (x) = x and an innite sum of sine 1 = − or 2 tan on ⎞ 2 x cos the 2 x sin inside function is v (x) = tan x. and cosine functions. The oscillation x Apply the chain rule twice. First 3 d f (x ) = sin (2 x ) 3 the outside function is u(x) = of a x 3 spring = ( sin = 3 (2 x ) ) and the inside function is v(x) and = movement 2 f ′( x ) ( sin (2 x ) ) sin (2x). Then ( cos when finding the of a the (2 x ) ) (2 ) pendulum derivative of sin (2x), the are outside 2 = 6 sin ( 2 x ) cos ( 2 x ) examples function is u(x) = sin x and harmonic inside function is v(x) = are trigonometric functions A used to motion? In questions 1 f 3 y (x) = 1–10, 3sin x – find the derivative 2cos x of each 2 y = 4 s (t) function. tan (3x) 2 2 = cos t sin x 2 5 f (x ) sin x 6 y 8 f = tan x 7 y = cos x 1 + sin ( 4 x ) (x ) = 2 cos ( 2 x ) 4 9 y 10 2 sin Calculus ( x ) with trigonometric functions f (x) = sin (sin x) simple motion. 2x. How Exercise of the and calculus model this EXAM-STYLE QUESTIONS Differentiate 11 with respect 3 tan a A 12 (x to x 4 ) cos b function has the x equation y = sin(3x – 4). 2 dy Find a d . y Find b 2 dx Example Find the dx equations of the tangent line and the normal line to the cur ve f (x) = cos 3x at the point where x 9 Answer p f 9 cos 3 9 Evaluate find of tangency = the point of to tangenc y. 1 is , 9 x 2 ( x ) at 9 f f 3 point function 1 cos The the 3 sin 2 3 x Find the derivative of f and ‘Slope’ p f 9 3 sin 3 9 3 sin 3 3 evaluate it at x to = find slope 3 3 of the tangent is another the word 9 for ‘gradient’. line. 2 3 2 x at 3 The 3 is 9 2 slope of the normal line at The 2 x 2 is 9 to or 3 3 nor mal the tangent negative line: y 3 3 x per pendicular so the slopes are 2 1 line: y 2 3 9 x 9 Use the line, y – y = 1 9 point–slope equation for a 2 reciprocals. 2 Normal is line, 9 1 Tangent line 3 m(x – x ), to write the 1 equations. Exercise In B questions normal line 1 to and the 2, find cur ve the at equations the given of value the of tangent line and the x. 1 f (x ) sin x cos x ; f (x ) 2 tan x ; x 2 2 x 4 Chapter EXAM-STYLE QUESTIONS Most ⎛ p The 3 point ⎞ P the on the graph of y = sin f (x) ⎠ gradient = elds of the tangent to the cur ve at can be Write b Find cos other P . by function. function is an An a function (2x). down the value that f of is algebraic, transcendental, or . a 3 f sciences, and modeled elementary a the (2x). elementar y Let 4 in business ⎟ 2 ⎝ Find lies ,0 ⎜ phenomena engineering , sum, difference, product, quotient ′(x). or composition of algebraic and Find c the equation of the tangent line to f x at transcendental functions. 3 Algebraic Consider 5 Find the the function value(s) of x f (x) for = 3 sin which x the for 0 ≤ x tangent ≤ functions 2π. lines ● Polynomials ● Rational ● Functions to functions 3 the graph of f are parallel to the line y x 4 involving radicals 2 Transcendental (cannot . More practice wi th be now know the derivatives of d these n radicals [x 1 nx ] = , n ≠ 1 [sin dx dx d d x [e x] = e ] = [cos x ] = 1 d [ln x ] = x , > sums, and involving x ) ● Logarithmic functions ● Exponential functions ● T rigonometric ● Inverse functions − sin x dx d as quotients cos x x dx products, n functions: d n expressed derivatives difference, Y ou functions trigonometric functions 1 0 [tan x ] = , cos x ≠ With 0 the exception of the inverse 2 dx x dx cos x trigonometric Using these facts and the r ules stated at the differentiate of Section variety of 14.1, can find the derivatives f the (x) you a wide any can now elementar y function. derivative of each function. 2x a of almost functions. Example Find you function, beginning = 4e 3 + sin (3x + 2) c y = d s(t) cos x sin x x b y = e sin x = ln(sin t) Answers 2x f a (x) = 4e ′(x) = 4(e + = 8e sin (3x + 2) Use the constant, multiple and chain rules to 2x f )(2) + [cos (3x + 2)] (3) dif ferentiate the first dif ferentiate the second ter m and the chain rule to 2x + 3cos (3x + 2) ter m. x b y = e sin x x y ′ = e x (cos x) + sin x (e ) Use the product rule. Use the product rule x = e (cos x = cos = (cos x) + sin x) 3 y c x sin x 3 sin x 3 y ′ = (cos x) 2 (cos x) 4 = d cos s (t ) = s ′( t ) = + 2 x – 3cos sin x (3(cos x) ) (–sin x) x sin when x finding Apply sin t Calculus with 1 cost (cost ) apply the chain 3 the derivative ln(sin t ) 1 and 2 = or sin t trigonometric tan t functions the chain rule. of (cos x) rule Exercise In C questions 1–10, find f 1 (x ) 6 cos 2x 3 (x) = of each y 2 = 1 + cos x x xe – function. sin x 3x x f derivative 3 the 1 e sin 2 t 4 s (t ) = e 2 x 5 f 7 y 9 f (x) = e (sin x – cos x) s(t) 6 = t tan t 3x = e (x) cos = (ln 4x x)(cos EXAM-STYLE x) 8 y 10 f tan 2 x (x) = ln (cos x) QUESTIONS 2 11 Let a f (x) = ln(3x ). Write down f ′(x). x g(x ) Let b sin . Write down g ′(x). 2 x 2 Let c h( x ) ln(3 x . ) sin Find h ′(x). 2 2 sin x Given 12 f that (x ) cos x (1 + a cos and f ′( x ) find Y ou a can and use + b sin x ) , 2 1 cos 2 x = 2 x (1 + cos 2 x ) b the first and second derivatives of a function See to analyze the graph of a Chapter Section Example Consider a Find 7, function. 7. the the function x- and f (x) = sin x + cos x for 0 b Find the inter vals on which f is increasing c Find the inter vals on which f is concave d Use the ≤ x ≤ 2π. Analyze it without using a GDC. y-intercepts. information from par ts a to c and up to decreasing and sketch concave the and down graph of the relative and the extreme inflexion points. points. f Answers To a sin x + cos x = find solve sin x = –cos 3 x x. x-intercept, Use your set the function knowledge of unit equal circle to 0 and values to x find 7 the solutions. 4 7 3 x-intercepts: and 4 (0) for , 4 f the 0 = sin 0 = 0 = 1 + + 1 y-intercept: 4 cos 0 To x find = the y-intercept, evaluate the function when 0. 1 { Continued on next Chapter page b f (x) f ′(x) = sin x = cos x – cos x = cos + x sin x cos x = ′(x) = 0 at 0 f is x f x 5 x x The – 5r 4 4 maximum point: , 0. and decreasing 2r Evaluate cos x – sin x – cos x – sin x = derivative at x that relative changes extrema sign. 5 and 4 find the maximum and minimum values. 4 Find = f us 2 , – first tells 4 to – sin x the 5 Relative minimum point: when test 2 4 derivative 0 f cos x the ″(x) Make 7 f is = a second derivative of f and find where 0. sign concave diagram up when f is for f ″ f is ″. positive and concave , 4 4 down when up: x f''(x) 4 – 0 3 down: 0 x x 2 7 3 , 0 and 4 – 7r 4 4 2r 4 Inflexion points: + 3r 7 and 4 Inflexion negative. 4 Concave ″ 7 3 Concave points occur when the , changes 0 second derivative 3 sign. Evaluate f at x 7 and to find 4 4 4 the d = + r first occur ′(x) negative. + 2 4 x positive is f 4 3 ′ where ′. 5 Decreasing: = f find f 4 0 ″(x) when and f'(x) and f is f for 4 4 c ′ of diagram , Relative derivative sign 5 0 a increasing when 4 Increasing: the Make sin x f Find – sin x y-coordinates of the inflexion points. f(x) r 2 √2 ( ) 4 1 x 0 –1 r r 3r 4 2 4 r 5r 3r 7r 4 2 4 2r 5r –2 , – √2 ( ) 4 Derivatives are useful for finding both relative extrema and Absolute absolute extrema on a closed extrema inter val. sometimes 'global Calculus with trigonometric functions called extrema'. are Example Show a f (x) how = ln x to + use the sin x on second 0 ≤ x ≤ derivative test to find the x-coordinates of the relative extrema of 2π 2 Find b the global extrema of the function f (x) = x + sin (x ) on the closed inter val 0 ≤ x ≤ π Answers Find f a (x) = ln x + sin it 1 ′( x ) = f the first derivative and set x equal to zero to find the critical + cos x x numbers. Use a GDC to solve. 1 + cos x = 0 x x ≈ 2.04, 4.48 Find the second derivative 1 f ″( x ) = − sin x and evaluate each of the 2 x critical f ″(2.04) relative f ≈ 1.11 < maximum ″(4.48) relative – ≈ 0.925 ⇒ at > minimum 0 0 at x = 2.07 f ⇒ x numbers derivative ″ > and = 0 f in the implies ″(x) < 0 from the second a relative implies first derivative. a minimum relative maximum. 4.49 2 f b (x) = x + sin (x ) Find the first derivative. 2 f ′(x) = 1 + 2x cos (x ) Set it equal the critical to zero to find 2 1 x + = 2x cos (x 1.392, ) = 0 2.115, 2.834 Use a Evaluate f (0) = f (1.392) ≈ 2.33 f (2.115) ≈ 1.14 (2.834) ≈ the The (π) at the the critical the first numbers is 3.82 and GDC the is is help and GDCs Exercise D Do a For maximum 1 f (x) = 2 f (x) = For 2 sin points. f x (x ) 2, of x + + find cos largest value is the global maximum and the the minimum. on CD: Alternative for find any x, ≤ 0 0 the ≤ concave points, 0 x x on ≤ the TI-84 ≤ to on the CD. minimum the given points and relative inter val. 2π up relative are FX-9860GII 2π intervals information sin x , relative x Casio 1–5. function 2x, decreasing, this questions the cos 3–4, minimum Use for and 3 sin questions relative 1 points increasing, 3 GDC questions from 0. Plus ✗ of 2.71 maximum use each derivative. The demonstrations not endpoints and 3.82 ≈ minimum solve. inter val smallest f f to 0 of f numbers. GDC on and which concave maximum sketch a the function down. points graph of Find and the is any inflexion function. 2 4 f (x) = cos (2x), 0 ≤ x ≤ π Chapter EXAM-STYLE QUESTIONS 2 5 Let f (x) = a Show b f has 0 ≤ x cos that one c Find f d Find the 6 may Let a f use (x) f ii b f a ≤ x + x can ≤ point coordinates of on the this inter val point. and x of the inflexion point(s) of f on the π ≤ for sin be questions 6–8. x expressed in the form ax sin x + b cos x. b the equation use minimum 0 minimum ′(x). Hence ii x –3sin 2x the GDC π = Solve i Find 0 ″(x) Find = coordinates a Find i ′(x) cos ″(x). inter val Y ou f + relative π. ≤ 2x f ″(x) to points f ′(x) = 0 identify and any for the 0 ≤ x 2π ≤ x-coordinate relative of maximum any relative points of f for 2π ≤ 2 7 Let f (x) = a Find f b Hence x cos x ′(x). 2 find inter val 8 The ≤ x milk pushes Suppose stirrer the that blade in is can the of machine Ghirardelli stirred blade the extrema f (x) = x cos x on the 5. shows Factory chocolate global ≤ photograph Chocolate that 0 the by back distance be a Square, stirrer and by San chocolate Francisco. that across the the stirs blade forth between modeled that is the center A driven bottom of the in The vat by of a of wheel the wheel vat. and the function 2 d (q ) = 2 cos q where the d is wheel the in + q 25 − 4 sin distance in metres and θ is the angle of rotation of radians. d ′(θ). a Find b Sketch i a graph coordinates maximum c i of of all d ′(θ) for 0 ≤ x-intercepts θ ≤ and 2π, and relative label the minimum and points. Explain how to use the graph of d ′(θ) to determine the d angle from of rotation the center when of the the blade wheel. is What at is the shor test this angle distance and this distance? ii At which center of Explain Calculus with angle(s) the how of wheel you trigonometric rotation and the determine functions is the blade your distance changing answer. between the the fastest? . Y ou Integral met these of sine integration and r ules in cosine Chapter 9. 1 n Power x rule: n +1 dx x = + C, n ≠ 1 n + 1 k dx Constant rule: Constant multiple Sum or dierence = kx + C kf (x) dx rule: ( rule: f (x) ± = k f (x) dx g (x)) dx = f (x) dx ± g (x) dx 1 x Integrals of and e dx : = ln x x e Integral with + C , x > 0 x x linear x dx = e + C composi tion: 1 f ( ax + b )d x = F ( ax + b) + C, where F ′(x) = f (x). a These of integrals sine and result directly from the derivatives cosine. Check: ➔ Integrals of sine and cosine d ( sin x dx = –cos x + C cos x dx = sin x + cos x ) = C dx −( −sin x ) = sin x d The integrals of the composition of sine or cosine with a linear (sin x ) = cos x dx function are: 1 ➔ sin (ax + b ) dx = - cos (ax + b) + C a 1 cos ( ax + b ) dx = sin (ax + b) + C a Y ou can perhaps f use the substitution recognize (g (x)) g ′(x) when you method have an to find some integral of integrals the or form dx. Chapter Example Find the integrals. a 3 sin x dx c e x b cos (4x d x x sin (e – 3 ) dx 6) dx 4 cos (3x ) dx Answers Use 3 sin x a dx = 3 sin x = 3 (–cos x) = –3cos x + + the constant multiple cos (4 x − 6)d x x e ( ax + b ) dx = sin ( ax + b ) + C a (e ) dx = ⎛ du ⎞ ⎜ ⎟ Recognize dx sin this as the for m u dx ⎠ f(g(x))g ′(x) = sin dx and write u du down let u = –cos u = –cos e + and C then use = e x and substitute e for u. x 1 3 + C u ⎛ du ⎞ 4 4 cos (3x ) dx = × ⎜ 12 ⎝ cos Let u dx u = 3x 3 and then = 12 x ⎟ dx x ⎠ 1 so ⎛ du ⎞ ⎜ ⎟ 3 = 12 ⎝ dx x ⎠ 1 = Simplify cos u du and integrate. 12 1 sin u + C = 12 1 4 4 sin = (3 x Substitute ) + C 3x for 12 Exercise Find the E integrals in questions 1–10. ⎛ ⎛ 1 2 1 (2cos x + 3sin x) dx 2 ⎜ x + cos π sin(π 5 20x x) dx 3 ⎝ ⎟ ⎟ 4 sin(2x 6 (2x + 3 (5x dx ⎠ ⎠ 3)dx 4 cos ⎞ ⎞ x ⎜ ⎝ 3 2 ) dx – 1)cos (4x – 4x) dx tan( 3 x ) e cos dx 7 (ln x ) 8 dx 2 cos (3 x ) x sin x 2 9 cos x sin xdx dx , 10 cos x Calculus with trigonometric answer x e dx = the du x or x sine. x sin ⎝ d integrate 1 cos − 6) + C 4 c then C sin (4 x = and C 1 b rule dx functions for cos x > 0 u. , . Simplify, integrate EXAM-STYLE QUESTIONS sin Let 11 f = a Find b Write Let 12 (x) f f (x) down = Show b Hence can cos x. ′(x). a Y ou x e use f (x) dx ln(cos x). that f ′(x) find the = –tan x. tan x ln(cos x) dx Fundamental Theorem of Calculus to evaluate definite See Section 9.4. integrals: b b f (x ) dx = [F = ( x )] F (b ) − F ( a ) , where F is an antiderivative of f. a a Example Evaluate Then the check definite your integral answer by without a evaluating GDC the to get definite the exact integral value. on a GDC. 2 4 3 a 2cos x sin( 2 x ) cos b dx ( 2 x )dx 0 4 Answers 4 4 2cosx dx a = 2 cosx dx Apply the Fundamental Theorem of Calculus. 0 0 p = 2 ⎡ sin x ⎤ ⎣ 4 ⎦ 0 p ⎛ = 2 ⎜ sin ⎛ = ⎞ − sin 0 4 ⎝ ⎟ ⎠ ⎞ 2 2⎜ 0 ⎟ Use unit circle values to evaluate. ⎟ ⎜ 2 ⎠ ⎝ = 2 Look Using a at the investigation in Section 9.3 if you need GDC: to review how to enter a definite integral into your calculator. 4 2 cos x dx ≈ 1.41 and since 0 2 ≈ 1.41, our answer is verified. GDC help on screenshots Plus and GDCs CD: for Casio are on Alternative the TI-84 FX-9860GII the CD. { Continued on next Chapter page 2 du 3 sin b ( 2 x ) cos Let ( 2 x )dx u = cos (2x) and = −2sin (2x) . dx p 4 x = 1 ⎛ du 2 ⌠ = ⎞ 3 u − ⎮ ⎜ 1 dx 2 x = dx ⎝ ⎛ du ⎞ ⎜ ⎟ 3 ⎟ Substitute p ⌡ ⎠ 2 4 dx ⎝ for sin (2x) and 3 u for cos (2x). ⎠ u=−1 1 = When − x ⎛ , u = cos 2 p 1 1 ⎡ 1 4 − When ⎤ ⎢ ⎣ ⎥ 4 ⎦ ( ( −1) cos ⎛ p ⎞ ⎞ ⎜ ⎟ ⎟ ⎝ 4 2 p = ⎠ ⎠ 2 = cos 0 2 cos 1 0 Then 4 − , 2 1 = = x u 2 2 ⎝ u=0 = ⎜ 4 − 0 apply the Fundamental Theorem of Calculus. ) 8 1 = − 8 2 3 Using a sin GDC: ( 2 x ) cos ( 2 x )dx = −0 .125 Evaluate the definite integral on your GDC. 4 1 and = since −0 125 , our answer is verified. 8 GDC help on screenshots Plus and GDCs Exercise Evaluate Then Casio are on Alternative the TI-84 FX-9860GII the CD. F the check CD: for definite your integral answer by without evaluating a GDC the to get definite the exact integral on value. a GDC. π 3 cosx dx 1 (2sin x 2 + sin 2x) dx 0 3 ln 3 2 3 2 cos x e 4 dx x x cos (e ) dx 0 3 ln 4 Y ou ➔ can use When the definite the lines x area = a integrals bounded and x = b to by is find the area and cur ve y rotated 360° = volume. f (x), about the the x-axis x-axis, and the y b 2 volume of the solid formed π y is dx. a 0 Calculus with trigonometric functions x Example A por tion a Find b Write of the the graph area of of the f (x) = shaded x sin x is shown in the y diagram. region. f(x) solid down the formed integral when the representing shaded the region is volume rotated of = x sin x the 360° A 0 about the Hence, x x-axis. find the volume of the solid. Answers Set x sin x a = of x = 0 x = 0, the function equal to 0 to find the x-coordinates 0 or sin x = O and A. 0 π Set π x (sin x )dx ≈ 3.14 up the Notice 0 definite that the integral area of and this evaluate region on happens a to GDC. be π b π 2 π y Use dx to set up the definite integral and 2 b ⎡ x (sin ⎣ π x )⎤ dx ≈ 13.8 a ⎦ 0 evaluate on a GDC. y Y ou can also find the area between two cur ves. Quadrant Quadrant 2 1 b ➔ If y ≥ y 1 for all x in a ≤ x ≤ b, then ( y − 1 2 y is )d x the area 2 a between Example Find the the two cur ves. x O Quadrant Quadrant 3 4 area of the region in quadrant 1 that is bounded by the cur ves y = 0.4x and y = sin x Answer 2.125 Use Area = (sin (x)) − a GDC to help sketch a graph and find the 0.4x) dx points of intersection where sin x = 0.4x. 0 b ≈ 0.623 The area is equal to ( y y 1 ) dx 2 a where Since a = 0 sin x choose y and ≥ = b 0.4x sin x ≈ 0 and y 1 Exercise In 1–2, integral 1 y = x 2 y = x ≤ x = ≤ 2.125, 0.4x. 2 G questions definite 2.125. for sin x a to and region find y = is the 2x – bounded area 6 in of by the the given cur ves. Use a region. quadrant l 2 – 2 and y = x + cos x Chapter EXAM-STYLE QUESTIONS k 1 3 Given that cos xdx and = f Let (x ) bounded a Find b Write tan by the f, x . the area down formed k , Consider x-axis of the the when the and the exact value of k region the line x in = the first quadrant 2. region. integral the find 2 2 0 4 0 representing region is rotated the 360° volume about of the solid the x-axis. y Hence find the volume of the solid. (r 2) 2 5 The graph represents the function f (x) = a sin (bx). 1 a Find the b Hence values of a and b x find the area of the shaded r region. –1 6 The y = a diagram cos y i x + = shows sin cos 2x. x + par t of the Regions sin 2x A can graph and be B of are written 3r r 2 5r 2r 3r 7r 2 r 2 –2 shaded. as y y = cos x(c + d sin x). Find the values of c and d 2 ii b Hence find shown in the the exact values of the two x-intercepts 1 diagram. i Find the area of ii Find the total A region A x 0 B c Find the rotated . area volume 360° of about Revisiting of the the the shaded solid –1 regions. formed when region A –2 is x-axis. linear motion Extension material Worksheet 14 - trigonometric Derivatives motion and along Suppose position that a s(t). straight an from function integrals object an We used in kinematics problems involving and derivatives integrals moving at any have along time the t is a straight given following by line the and that its displacement relationships. Remember Displacement function CD: line. is origin then are on More = that… s (t) Initially ⇒ at time 0 ds = v (t ) = Velocity s′(t) At rest ⇒ v(t) = 0 dt Initially at rest dv Acceleration ⇒ a (t ) = = v′(t) or v(0) = 0 s″(t) dt Moving right or up t 2 ⇒ T otal distance traveled from time t to = t Moving t We will now modeled by Calculus look at some trigonometric with trigonometric examples functions. functions v(t) > 0 |v (t)|dt where the linear motion is ⇒ left v(t) Speed = < or down 0 |velocity| Example A par ticle moves along a horizontal line. The par ticle’s displacement, in metres, from an origin O is given by s(t) = 5 – 2cos 3t a Find the par ticle’s velocity b Find the par ticle’s initial c Find when stopped d Write the par ticle during down traveled for a 0 the definite ≤ t π ≤ is time and acceleration displacement, moving 0 ≤ t ≤ integral seconds to for time t seconds. at any velocity the right, time and to the t acceleration. left and π that and represents use a the GDC to total find distance the distance. Answers a v(t) a(t) b s(0) v(0) = 0 – = 6sin 3t = 6(cos 3t)(3) = 18cos 3t = 5 – 2cos (3(0)) = 5 – 2(1) = 6sin (3(0)) = 6(0) = 18cos (3(0)) = 18(1) v(t) = s′(t) a(t) = v′(t) 2(–sin 3t)(3) = Evaluate each function at t = 0 3 m –1 a(0) = 0 m s –2 c v(t) = = 18 m s 0 6sin 3t sin 3t 3t The = = = 0 v(t) 0 0, when π, 2π, t 0, 0, v(t) < 0. helpful > A to at rest when par ticle 0 and sign moves left when diagram analyze the right is motion. 3 is at rest v(t) at + – + 2 The and , 3 0 seconds. r 2r 3 3 3 par ticle moves 0 v (t) is 0. The , , par ticle 3π 2 3 The par ticle = t t and 3 for 2 seconds right r 3 and left for 2 t 3 seconds. 3 π d |6sin 3t| dt = 12 m The total t t distance traveled from time 0 t 2 to 1 is |v(t)| dt. Use a GDC to 2 t evaluate the integral. GDC help on screenshots Plus and GDCs CD: for Casio are on Alternative the TI-84 FX-9860GII the CD. Chapter Example –1 A par ticle moves along a straight line so the par ticle when that its velocity , v m s at time t seconds is given by 2 v(t) = 5sin t cos t 5 Find a the speed of t seconds. 6 b When t = 0, the displacement, Find an expression for s c Find an expression for the in s, of terms of the par ticle is 3 m. t. acceleration, a, of the par ticle in terms of t Answers a 5 v 6 5 2 5 sin 5 Velocity cos 6 6 has both magnitude and direction, and speed is speed = the magnitude of velocity. Therefore 2 1 5 2 3 |velocity|. 2 15 8 15 Speed 15 = = 8 ∫ 5 sin t cos t dt = ⎮ du ⎛ ⌠ 2 b 1 m s 8 5 ⌡ ⎞ 2 u − ⎜ dt Integrate ⎟ dt ⎝ velocity to get displacement. ⎠ Using substitution let u = cos t, 2 5 = du u ∫ du then = − sin t = sin t dt ⎛ 1 = −5 3 ⎞ + C u ⎜ ⎝ du ⎟ 3 ⎠ so − dt 5 3 s (t ) = − cos t + C 3 5 3 3 = − (0 ) + C cos Use the fact that Use the product s(0) = 3 to find C. 3 5 3 = − (1) + C 3 14 C = 3 5 14 3 So s (t ) = − cos t + 3 a (t ) c = 3 v ′( t ) 2 = 5 sin t [ 2 (cos t )( − sin t ) ] + cos 2 = ✗ −10 sin Exercise H Do a not use 1 A particle of rule and velocity. t (5 cos t ) 3 t cos t GDC EXAM-STYLE derivative for + 5 cos t question 1–3. QUESTION moves along a straight line so that its displacement s in t metres from an origin O is given by s (t) a Write down an expression for the b Write down an expression for the Calculus with trigonometric functions = e sin t velocity , v, for in time t terms acceleration, a, in seconds. of t terms of t the chain rule to find the 2 A par ticle moves displacement, s (t) = 1 – 2sin Calculate a in t along a metres, for the time straight from t velocity when Calculate the value c Calculate the displacement is The origin O par ticle’s is given by seconds. b velocity line. an of t for t = 0 0. < of t π < the when the par ticle velocity from O is when zero. the zero. –1 3 The velocity v m s of a moving body along a horizontal line at sint time a t seconds Find i 0 ii t the ≤ ≤ The in may t the a par ticle the body’s initial use v (t) = is e at cos rest t during the inter val par ticle is moving left during the inter val 2π terms object by 2π ≤ 0 c An when when Find Y ou given Find b s 4 ≤ is acceleration displacement of s is a in 4 terms metres. of t Find an expression for t GDC star ts for by questions moving 4–6. from a fixed point O. Its velocity –1 v m s Let after d be t the seconds is given displacement a Write b Calculate down an the from integral value of by v (t) O which = 4 sin when t = t + 3cos t, t ≥ 0. 4. represents d d −1 5 A par ticle moves with a velocity v m s given by 2 ⎛ v (t ) = −( t + 1) sin ⎞ t where ⎜ t ≥ 0. ⎟ 2 ⎝ a i Find ii A the acceleration par ticle have the b Find all c Find the 0 < < t at speeding sign at times 1.5 when the 1.5 seconds. velocity slowing whether time in time up and Determine down the changes is same different. slowing ⎠ down the and acceleration when par ticle is the signs speeding are up or seconds. inter val 0 < t < 4 that the par ticle direction. total distance traveled by the par ticle during the time 4. −1 6 The velocity , v, in m s of a par ticle moving in a straight line is 2sin t given 0 a ≤ t by ≤ v (t) = e – 1, where t is the time in seconds for 12. Find the acceleration of the par ticle at t =1. 2sin t b i ii Sketch a graph Determine the of v(t) = value(s) e of – t, 1 for for 0 ≤ 0 t ≤ ≤ t ≤ 12 12. where the particle −1 has iii At a velocity time velocity origin c Find the t = to in of 0 5 the m par ticle explain the s whether inter val distance is 0 ≤ traveled t in ≤ at or the origin. not the Use the par ticle graph retur ns of to the 12. the 12 seconds. Chapter Review exercise ✗ 1 Find the derivative of 3 f a (x) = cos tan = (1 – 2x) b y d f = sin x 2 t c s (t) e e f (x) = x g f (x) = (ln (x ) sin x 2 2 Find the cos x x)(sin integral x) f y = ln(tan h y = 2 sin x) x cos x of 3 a ( c sin ( 4 x 4x ) − sin x b dx cos (3 x )d x 2 sin ( 2 t ⌠ e + 1)d x + 1) f ( 2t ⌡ + 1) 2 sin x cos x Evaluate the x 6 cos x ⌠ 2 xe dx h definite dx ⎮ ⌡ 3 dx ⎮ 2 cos ⌡ g )dx sin (ln x ) ⌠ dt ⎮ x cos ( 2 x d 2 ( 2 + sin x ) integral of π 3 sin x dx a (1 b + sin x) dx 0 3 π 3 2 2 (sin x c + cos 2x) dx 5 sin d 0 EXAM-STYLE 4 Find y = x cos x d x 0 the QUESTIONS equation cos (3x – 6) at of the the normal point to the cur ve with equation (2, 1). 5 Find the coordinates of the point on the graph of y x , sin 2 1 0 ≤ x π, ≤ at which the tangent is parallel to the line x 3 4 6 A curve with equation y = f (x) passes through the point (0, 2). Its f (x) gradient function is f ′(x) = x – sin x. Find the equation of the curve. 4 7 The graph represents the function f (x) = p sin(x) + q, p, q ∈ Find 2 a the values b the area of of p the and q shaded region. x 0 r 2 Review 1 A to region find exercise is the bounded area of by the the given cur ves. Use a definite region. 2 a b y y = 2cos Calculus x + 2 sin x with cos and x y + = trigonometric 1, x = 0, 0.5x functions x = 2 and the x-axis integral r 3r 2 2r 2 A to region find 360° a y is the bounded volume about = sin the x by of the the given solid cur ves. formed Use when a definite the region integral is rotated = k, x-axis. and the x-axis for 0 ≤ x π ≤ cos x b y = e , EXAM-STYLE 3 The area x = 0 and x 2π = QUESTIONS under the cur ve y = cos x between x = 0 and x 0 where k , is 0.942. Find the value of k 2 cos 4 Let a s(t) = (5t) 2e – i Find ii Show iii Hence 4. s′ (t). cos that s′′ (t) = (5t) 50 e 2 (sin (5t) – cos (5t)). verify that s has a relative minimum at t 5 b s is the displacement straight line, where Find the total t to = = 0 t 2 CHAPTER f (x) f (x) = = sin of x cos measured traveled a par ticle in by moving metres the and par ticle t is along in a seconds. from SUMMARY of trigonometric sine, ⇒ x is distance 14 Derivatives s for seconds. Derivatives ● function f ⇒ f cos ′(x) = ′(x) = and cos – functions tan: x sin x 1 f (x ) tan x ( x ) f , cos x 0 2 cos Integral ● of Integrals of sin xdx = cos xdx = sine sine sin x ⎮ 1 sin (ax + b )d x = − cos (ax + b) + C a 1 ⌠ cos ( ax + b )d x sin ( ax = ⌡ ● cosine: + C ⌡ ⎮ cosine + C ⌠ ● and and − cos x x + b) + C a When the lines = x a area and bounded x = b is by the rotated cur ve y 360° = f about (x), the the x-axis x-axis, the and the volume b 2 of the solid formed πy is dx a ● If y 1 ≥ y for all x in a ≤ b x ≤ b, then (y 2 1 − y ) dx is the area 2 a between the two cur ves. Chapter Theory of knowledge From conjecture The investigation into the to derivative of proof sine in Chapter 14 graphed the d derivative of sin x, which led to the conjecture that (sin x) = cos x. dx This was tested with several values and found to be tr ue for these values. d Does this prove that (sin x) = cos x? dx Follow TEP S Here is a For these each steps step, to find are you the derivative using inductive ONE: unit of or TEP S circle. QOP = h radians. As h using geometr y . deductive reasoning? TWO: approaches length S sine of arc QP zero, how compare does to the the length of Q segment QP? S P Q h x O P R h x R QOP is π – isosceles? h hy radians? 2 y TEP S i rc Q ? THREE: S Q π Why is SOQ equal to – h – x? 2 F ind a line segment parallel to SO. π Hence, why is OQA also equal to – h – x ? 2 A P h Use OQP and OQA to explain why AQP = + x h . 2 x O Theory of knowledge: From conjecture to proof R TEP FOUR: S Why does QA TEP FIVE: S equal sin (x + h) – sin x ? d Now show that (sin x) = cos x. dx S Q (cos (x + h), sin (x + h)) Explain each line of wor king: h + d x 2 sin (x (sin x) = + h) – sin x lim dx h h→ 0 QA = lim arc QP h→ 0 P A (cos x, sin x) QA = lim QP h→ 0 h h x = lim [cos + x] 2 h→ 0 O R = cos x S Q “Ever y meaningful mathematical h + statement can also be expressed in sin (x language. Many + h) – sin x plain-language A statements of x 2 plain mathematical P expressions h x would fill several pages, while to express O them in mathematical notation take as little as one line. One R might of the Which type of reasoning did you use to d show ways to achieve this that remarkable (sin x) = cos x? Deductive or dx inductive? compression is to use symbols to stand for statements, instructions and so Explain the Lancelot Hogben The underlying English for with an example of other type of reasoning. d Does this prove that (sin x) = cos x? symbols concepts mathematician credited Give dx scientist Mathematical answer . (1895–1975) English your on.” of calculus John introducing the Wallis is symbol ∞ innity. Could calculus without the have use of developed mathematical symbols? { ) Chapter Probability CHAPTER OBJECTIVES: Concept 5.7 distributions of Expected discrete value random (mean), E(X) variables for and discrete their probability distributions. data. Applications 5.8 Binomial 5.9 Normal distribution distribution Standardization Proper ties Before Y ou 1 e.g. the you should Calculate of distribution the of normal normal how mean Calculate its mean and variance. cur ves. variables (z-values) distribution start know the of and and of a mean to: set of of this Skills numbers 1 frequency check Calculate the distributions x. mean of of these frequency x: a x x 0 1 2 3 Frequency 3 6 9 2 Frequency 3 4 5 6 7 8 3 5 7 9 6 2 b x f ∑ x x ( = 0 × 3) + (1 × 6) + ( 2 × 9 ) + (3 × 2 12 15 17 20 3 10 15 9 2 Frequency = ∑ 10 ) f 3 + 6 + 9 + 2 Repeat question 1 above using your 30 = 1 = GDC. 5 20 2 Evaluate ⎛ n ⎞ 2 Use ⎜ ⎟ notation ⎛ 8 ⎞ ⎛ 6 ⎞ r a ⎜ ⎟ ⎛ 5 ⎞ 2 ⎝ e.g. ⎜ b ⎝ ⎠ ⎟ 5 ⎛ 9 ⎞ c ⎠ Evaluate ⎜ ⎟ 2 3 ⎛ 5 ⎞ ⎜ ⎝ ⎟ 2 5! 5 = Solve these equations 4 = 2 !3! ⎠ × = 5 10 5 = 3 a 2 2 x 3 Solve equations x 2 5 4 e.g. Solve the equation = 3 = b 1 0 2 x 4 9 4 = 3 4 = 3x x = 1 0 x Probability 3 distributions x c = 2 6 4 ⎜ ⎝ ⎟ 6 ⎠ 3 ( 0 .3 ) 6 ( 0.7 ) The the 2010 Soccer octopus matches Center correctly between in after a of marked match his 2008 and with were the placed of in the 2010! behavior matches. flag produced Germany , feeding soccer Cup predicted Oberhausen, famous series World Two one his of tank. an results Paul and was of lived in to each national His 12 became used boxes, the unlikely choice celebrity . out a of tank 14 in football the Sea Life inter nationally predict the containing teams of Paul in which a an winners mussel of and upcoming mussel to eat Why do believe first was inter preted as predicting that the countr y with that that to someone something (like an win. octopus) Paul was This chapter right 86% of the time! the can future rationally, will look at situations like this and how to probability of an event if it were entirely due to chance. 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Chapter . ➔ A Random random Random Here is variable variables are variables some are a quantity represented examples of whose by random value capital depends on chance. letters. variables: A X = the number of sixes obtained when a dice is rolled 3 discrete variable B = the number M = the mass of babies in a random times. does necessarily of crisps in a = the time taken for a r unner to complete just are two basic types of random shoe variables: values sizes students Discrete number random of – These variables possible values (e.g. X have and B a finite or countable possible above). …4, 6, Continuous some random inter val (e.g. – variables M and T These can take on any value the obtained discrete when represent ‘the a dice is (e.g. a could set have values 5, of of 5.5, in above). random variable X, rolled probability 4.5, of 6.5,…). Use Consider to positive 100 m. integer There need packet take T not pregnancy that 3 times. the the Y ou number number can of of write sixes sixes P(X is x’ = random x) where capital lower to x the can letters variables. case actual letters for Use for measured values. take the The values rst random statistician, By 1939 Bernard T o use a in set such a (up, example, 1927. of Most computers numbers 20, These which appearance of A of at 44, and are are took digits the right, the 62, a numbers by ‘at specialized point, diagonal, by the on from before Kendall of row by digits, selecting 5th an census operated number the Tippett, Maurice machine etc.) number , Leonard random’ published star ting the going English fact can now be pseudo-random by a used to numbers: mathematical generate that formula is, Probability distri bution possible that 63873 90708 20025 98859 23851 27965 62394 33666 62570 64775 78428 81666 26440 20422 05720 15838 47174 76866 14330 89793 34378 08730 56522 78155 22466 81978 57323 16381 66207 11698 99314 75002 80827 53867 37797 99982 27601 62686 44711 84543 87442 50033 14021 77757 54043 46176 42391 80871 32792 87989 72248 30500 28220 12444 71840 and a human. and the numbers. random are which have the of discrete variables each 78134 58303 numbers. distributions probability 45963 02965 backwards they but 73735 registers. ... calculators in published was 15th generated probabi li ty list left, was using decide random Probability random Smith down, 3. table 100 000 list, 22, numbers. and Tippett star ting 40, 2 number gives ➔ 1, Babington direction For 0, value each distributions for of a discrete the outcome random random occurs. variable variable and the is a Example Let X be rolled the three random times. variable Tabulate that the represents probability the number distribution of for sixes obtained when a fair dice is X Answer X can take the values 0, 1, 2 and 3 1 1 6 six P(3 sixes) = 1 1 × 6 1 × 6 1 Use a six P(2 sixes) = six 6 1 1 1 not 5 6 1 six 6 not 5 values to of 5 = 6 216 P(2 sixes) 5 × = 6 1 P ( X = 0), P ( X = 1), × 6 5 P(X = 6 = P ( X 1 not 5 P(1 six) = six 5 × 6 5 × 6 2) and 216 six 6 the 1 six 6 5 × × 6 diagram 216 find 6 tree = 6 = 3) 25 = 6 216 6 1 5 six P(2 sixes) 1 × = 1 × 5 = 6 6 6 6 216 1 six P(1 5 six) = six not 1 5 not 6 5 5 × × 6 6 25 = 6 216 6 1 6 six 5 six 6 P(1 six) = not 5 × 6 5 1 × 6 25 = 6 216 six 5 not 6 P(0 5 sixes) = six 5 × 6 5 × 6 125 = 6 216 6 x 0 1 2 3 Write P(X in 125 25 5 1 216 72 72 216 a the probabilities table. x) = Sometimes Notice that in the example the sum of the probabilities replaced 125 5 25 + 216 ➔ For + any = 72 72 ≤ P(X = P x) ≤ – these variable 1 same ∑ P( X = x ) ≤ P(X = x) random that variable X has the probability 1 2 3 4 5 7c 5c 4c 3c c of the value of c b Find be between 0 distribution means x) Find a must 1. P( X x a 1 and = ≤ 1 = always P (X mean thing. probability The is P(x) X means Example x) x 1 0 0 = just 216 the random with 1 or + P(X is P (X ≥ the that 1 the sum probabilities always 4) x) be will 1. Answers a 7c + 20c 5c = + 4c + 3c + c = 1 Using P (X 1 Solve 1 c ∑ for = x ) = 1 The solutions lots of of c examination = 20 questions b P (X ≥ 4) = P (X = 4) + P (X = 5) 3 = + 20 4 1 the fact that probability with the must total add = = 20 1 star t 20 5 up to 1. Chapter Exercise 1 Decide A a is on 2 3 A whether ‘the my age B is ‘the c C is ‘how d D the cats diameter the I of variable years the sum the number of the c the smaller d the product of or of the dice banana will see is continuous the two number faces has in distribution when a next or person when the for first discrete: to call me two one shopping’. white one’. cafeteria’. each ordinar y when on buy the when when ‘1’ I before donuts obtained equal of six-sided faces sixes next the probability b fair of many a A completed length ‘the Tabulate in random phone’. b is each two two random dice are ordinar y face, thrown ordinar y ordinar y a ‘2’ dice dice dice on variable: are two are are thrown thrown thrown. of its faces A and a ‘3’ on the remaining three fair dice The dice is thrown twice. T is the random variable ‘the thrown’. a the probability distribution b the probability that A board at a A fair S is If game time, the the played following that that to is equally land on any of this dice is of total by faces. T score moving a is more than counter S 4. squares forward r ule: thrown once. If the number shown is even, the number shown on number. number Write a is six-sided half a Find the 4 means total likely score dice faces. out shown a table is odd, showing S is the twice possible values of S and the dice. their probabilities. What b is counter 5 The the moves random x P(X = probability variable 1 2 1 1 3 3 x) a Find the b Find P(1 Exam-Style more value < X X 3 4 c c of < that than has 2 the in a single go in the game the spaces? probability distribution c 4). Question In 6 The probability distribution of a random variable Y is given question by 6, 3 P(Y = y) = cy 3 P(Y = y) = cy for y = 1, 2, 3 This Given that c is a constant, find the value of c is called probability function Y. use Y ou nd can the various random Probability distributions a it probability values of variable for to at the Y Exam-Style 7 The Questions random x variable −1 0 X 1 2 P(X Find 8 The x) = the 2k random of this probability distribution. 2 2 4k value has 6k k k variable x X has the probability distribution given by 1 1 P (X x ) k Find 9 The 3, the exact discrete 4, 5. The x = 1, 2, 3, 4 and value of random X can distribution take of X = 0) = P (X = 1) = P(X = 2) = a P (X = 3) = P (X = 4) = P(X = 5) = b P (X ≥ a = and 3P (X < are constants. a Determine the values b Determine the probability obser vations discrete these = The and from random only is the given values 0, 1, 2, by of this a and that b the distribution variables A and sum of two exceeds B are independent 7. independent and have = 1 2 3 1 1 1 3 3 3 1 2 3 1 2 1 6 3 6 a) B P (B constant. distributions: A P (A a 2) b The is k variable probability 2) k P (X where 10 for 3 b) random one variable obser vation C is the from sum of one obser vation from A B 5 a Show that b Tabulate P(C = 3) = 18 the probability distribution for C Expectation The mean value that or we expected should value expect of for a X random over variable many trials X of is the average the experiment. Expectation is actually mean of the the underlying distribution (the population). The mean or expected value of a random variable X is is parent often represented denoted by It by μ E (X). Chapter Investigation T wo D, dice are between Copy 1 rolled the and – together scores on complete d dice 0 and the the 1 scores the dice difference, is noted. probability 2 3 distribution 4 for D. 5 10 P(D = d) 36 This 2 experiment following each of table the is to repeated show different d 0 the values 1 36 times. expected of Copy and frequency complete of the obtaining d 2 Y ou 3 4 5 to may draw nd a it helpful sample Expected space diagram like 10 frequency ones 3 Calculate 4 The the original questions mean of experiment 2 and d 3 for 0 What do 6 What would we by would can just (the ➔ you the = Example is ∑ 2 of x be if 3 or each to = be value value Or 4 the of a of the same by of its the each the case. random respective just variable X Therefore variable D probability once). is x ) probability x from What expected of in experiment random repeated once? value d were distribution is Repeat 5 experiment just expected conducting P( X the times? mean mean expected E (X ) mean 1000 multiplying The Here Or the equivalent times. notice? the expect find 100 situation: 9 5 We repeated this distribution. 250 frequency times? is frequency 1 Expected 10 this the Example 0 1 2 3 1: value P (X = 125 25 5 1 216 72 72 216 x) X ? Answer Using the formula: Use 125 ⎛ E( X ) = 0 × 216 ⎝ ⎜ ⎠ ⎝ 5 ⎛ 2 ⎞ × 72 = (X ) ∑ x P (X = x ) × ⎟ 72 3 ⎟ ⎜ ⎠ ⎝ ⎠ 1 ⎛ + ⎜ ⎝ 1 ⎟ E 25 ⎞ ⎛ + ⎜ + ⎞ ⎞ × ⎟ 216 Therefore if 3 dice are rolled a large ⎠ number of times, you should expect 1 E( X ) = the mean number of sixes to be 0.5. 2 { Probability distributions Continued on next page in Chapter 3. the Using a GDC: Enter the list of possible x-values GDC help on CD: demonstrations in x and the set of Now use when Use x P(X = One-Variable finding as the Frequenc y Note values that the X1 mean List x) in p. Statistics of and a p not are = x = Exercise 1 When What The the expected to be a value value of of X X more defined is the entering see Chapter 17 obtainable. 5.1 and 5.2 a standard by X = six-sided the expectation square of of dice, the let X score be the random shown on the dice. X? Question z variable 2 = on that Sections random P (Z CD. B Exam-Style 2 the the 0.5 throwing variable on List. need actually TI-84 FX-9860GII set. data, is E(X) Casio as data as and GDCs For does the cor responding Plus probability Alternative for 3 1 1 6 6 Z has 5 probability 7 11 x y distribution 1 z) 6 2 and E( Z ) = 5 3 Find x 3 A and ‘Fibonacci numbers: What is 4 y The 1, the dice’ 2, 3, is 5, unbiased, 8, expected discrete random six-sided and labeled with these 13. score when variable X the has dice is rolled? probability distribution x p( x ) for x = 1, 2, 3, …, 8 36 Find E(X). Chapter Exam-Style 5 For the given Questions discrete random P, the probability distribution is by ⎧ kx ⎪ P( X variable = x ) = x = 1 , x = 2, 3, 4, 5 ⎨ ⎪k (10 − ⎩ x ) 6, 7, 8, 9 Find a 6 a the value Copy for a of and the complete, discrete x P (X b c 7 X What a Find in is a is ≤ discrete 1, 2 Ten but and are R and a in the Calculate c What balls this probability distribution can k take? Give your answer in the Q mean of the variable which 2) and distribution. can only take the three = 0.3 that the mean of the bag. are out They red at are and all the random identical rest are from sizes blue. the bag the the are balls red drawn out up to one. values most in drawn. mean a of the value likely bag random, that of first R and their probabilities. next Show a the at a the = number picked is P(X possible b Ten k, X: replaced. associated 9 k of 4. picked is ∈ b random them the of terms variable, 2.8. including List a, E(X) b 3 values b, k 1). not be is are of are of that = balls Balls Let P(X two 1−k and distribution 8 0.2 terms known Find 2 ≤ k in random 1 range form values It x) = constant as but, in of R value of R? question instead, probability 8 each that above. ball the is first Again, replaced red is balls are before drawn out the on the 4 second go is 25 b Calculate third c probability that the first red is drawn after the go. Derive drawn d the What Probability a formula on is the the nth most distributions to find the probability go. likely value of R? that the first red is Exam-Style 10 An instant are $0, Question lotter y $2, $20, representing z $200 1000 0.2 0.05 0.001 0.0001 P(Z E(Z) c How much = should of a are or ve ‘false’. may need 2 On 3 Bowling 4 It 5 Selachophobia average, look answers were T o is The its expect to the ticket. Z has the variable distribution: meaning. to gain or lose on average ve ‘test’ the at you ten of the answer that elements each to question each some by a move days light back many need quiz of is either question. them! woman. 300 000 times a day. Italy. questions. the to created in to answer answer fear How probability essential binomial answer V inci the score? guessing the da is distribution muscles’ played Answers these this The was ‘eye rst Leonardo in the the vest the was good just pass What ➔ a random prizes distri bution down guess bulletproof took – Write to The this you questions. 1 Is inter pret binomial Investigation Now the possible 0). and binomial Definition Y ou the The ticket? The ‘true’ on $2. be 200 Determine won Let Z 20 Determine Here $1000. for 2 b . and purchased amount a per is the 0 P (Z) ticket of How get a 3 paint the Mona book many you ever y get you of would to to to Lisa’ s lips. ashes. did to you expect nd get to the correct right? get right if you question? correct exactly binomial 3 out of right 5. out of distribution 5? ● In the ● Here, quiz above success is there are getting 5 trials. the are: question ● There ● Each is a fixed number (n) of has only two possible outcomes – ● The or a to question In this of a success (p) is getting case wrong. of success the probability is 0.5 assuming constant you trial is ‘failure’. probability from failure a ● ‘success’ and trials. the trial right obtained ever y answer by trial. guessing. ● Trials are independent of each other. ● If you get question you the are the answer right, more answer to it or to does less the one not likely next mean to get question right. Chapter The outcomes probabilities of of a binomial these ex p e r i m e n t o utc om es a re and ca ll ed a the cor respon d ing binomial distri bution The binomial variable ➔ X The the if distri bution the success). Consider the conditions parameters values this of n Any that (the of above define a number binomial problem, probability describes behavior unique of you exactly of a discrete apply . binomial trials) distribution which getting the first two and p is distribution (the probability represented met in heads as X Chapter in three 3: ∼ are of B(n, a p) determine tosses of a 2 biased coin for which P(head) = 3 Y ou could use a tree diagram to help you answer this question. 2 H 3 HHH 2 H 3 1 T HHT H HTH 3 H 2 2 3 1 3 T 3 T HTT 1 3 2 H THH 3 2 H 3 1 T THT H TTH 1 3 T 3 2 3 1 T 3 T TTT 1 3 P(two heads in three tosses) = P(HHT) + + P(HTH) P(THH) We Each of the three probabilities are the often use a theoretical same. distribution, such distribution, to as the binomial 2 P(HHT) = P(HTH) = P(THH) = 2 1 4 describe a random 3 3 variable 27 This that process occurs is in called real life. modeling and 2 And so P(two heads in three tosses) = 3 2 1 However, number What if you of trials, you obtaining should n, were exactly only is a tree 3 diagram 4 enables us tree diagram for so we Probability will look out calculations. 27 if 9 If the theoretical the real-life the model distribution variable matches perfectly, then the is to find heads in the six probability tosses of of this coin? usually not results of perfect. this question would be for distributions a formula. the any necessarily However , case. this calculations give of Generally is a the will completely real-life the not accurate situation. too Does large, carr y 3 description The to small. asked two use 12 this make them any less useful? First note been met: ● that There is the a conditions fixed number for (n) a binomial of In distribution this case have there are six trials. trials. ● Each trial outcomes has – a two possible ‘success’ or Here a a a success failure is is getting getting a a head and tail. ‘failure’. ● The probability of a success (p) 2 is The constant from trial to probability Trials are independent of each the Getting affect combination of Hs success and each is trial. other. One a 3 time ● of Ts that will coin a is head the tossed. on one outcome produce 2 heads of and trial the 4 will next not trial. tails The is most usual error HHTTTT when 2 2 calculating 4 binomial And P(HHTTTT) = ( 3 ever y possible probability 0.00548...) 3 729 is to forget there And combination of 2 Hs and 4 Ts will have are that r the there probability . must But if exactly successes, same a 4 1 how many combinations are also be n – r failures. there? ⎛ n ⎞ ⎜ ⎝ ⎟ r represents the number of ways of choosing r items out of For more binomial n on the ⎠ expansion, items. see The number of combinations ⎛ 6 ⎞ and 4 Ts is therefore ⎜ ⎝ ⎟ 2 of 6 items that have 2 Chapter 6. Hs ⎛ 6 ⎞ = ⎠ ⎜ ⎝ ⎟ 4 = 15 ⎠ ⎛ 6 ⎞ Y ou can use your GDC to calculate ⎜ ⎝ ⎟ 2 ⎠ GDC help on CD: demonstrations Plus and GDCs ⎛ 6 ⎞ Instead, you could use the formula ⎜ ⎝ ⎟ 2 6! = Casio are on Alternative for the TI-84 FX-9860GII the CD. 6 × 5 = 15 = 2! 4 ! 2 ⎠ or the 3rd entr y on the 6th row of Pascal’s triangle: Therefore 2 P(2 heads in 6 tosses) = ⎛ 6 ⎞ ⎛ ⎜ ⎟ ⎜ ⎠ ⎝ ⎝ 2 2 4 ⎞ ⎛ 1 ⎞ ⎟ ⎜ ⎠ ⎝ 4 = 15 3 × 20 = = 0. 0823 ( 3 sf ) ⎟ 3 ⎠ 729 243 Chapter Generalizing this method gives the binomial distribution function: ➔ If X of is binomially obtaining the r distributed, successes probability of success ⎛ n ⎞ P( X = r ) = ⎝ This is often r = r ) shor tened ⎝ X is r p = ⎜ Example − n B(n, p), then independent each trial, the probability trials, when p is is r ) n to r q where ⎟ r p ∼ ⎠ ⎛ n ⎞ P( X n (1 ⎟ of for r p ⎜ out X q = 1 – p ⎠ binomially distributed with 6 trials and a probability of success 1 equal to at each attempt. What is the probability of 5 a exactly c three four or successes fewer b at least one success? successes? Answers By hand: You 4 a P( X = 4) = ⎛ ⎜ ⎟ ⎜ ⎠ ⎝ ⎝ ⎠ ⎝ 4 5 1 = 15 × rewrite ⎞ ⎟ 5 X ~ B the question as ⎞ , 6, ⎜ what is ⎟ 5 ⎝ ⎠ 16 1 ⎛ If ⎟ ⎜ 4 can 2 ⎛ 6 ⎞ ⎛ 1 ⎞ a P (X = 4 ) b P (X ≥ 1) c P (X ≤ 3) ⎠ × 625 25 48 = ⎛ n ⎞ r 3125 Use P(X = r) = ⎜ ⎝ = 0.015 36 = 0.0154 (3 ⎟ r p n – r q ⎠ sf) 6 b 4 1 For P(X ≥ 1 P(X = 1) it is quicker to calculate 5 − 0) than to calculate 4096 P(X = 1 = 1) + P(X = 2) + ... + P(X = 6) 15 625 11 529 = 15 625 = 0.738 (3 sf) c P (X ≤ 3) = 0.983 P(X ≤ 3) = P(X = 0) + P(X = 1) + It P(X = 2) + P(X = 3) Use the your GDC Probability distributions this calculation (see following). { for is P(X so easy < r) read the carefully. Continued on next page to and confuse P(X ≤ r) questions GDC Using your help on CD: Alternative GDC: demonstrations Plus a and GDCs Casio are on for the TI-84 FX-9860GII the CD. b c Exercise 1 X is C binomially distributed with 4 trials and a probability 1 of success equal to on each trial. 2 Without a a P(X = c P(X ≤ calculator 1) 1) If X ~ B the probability b P(X < d P(X ≥ of 1) 1) 1 ⎞ ⎛ 2 determine 6, find ⎜ to 3 significant figures ⎟ 3 ⎝ In question and a P(X = c P(X ≤ 2) b P(X < d P(X ≥ d use 2) the you X is c binomially distributed with 8 of Binompdf 2) on If b Binomcdf 2) instead 3 2 ⎠ trials and a probability of calculator , are as calculating cumulative a probability. 2 success equal to at each attempt, what is the probability of 7 a exactly c more 5 successes than 5 successes b less d at than least 5 successes one success? Chapter Example The probability What get a is the bus that I get probability only a bus that in to a work on working any mor ning week of five is 0.4. days I will twice? Answer By hand: Let I X get X ∼ be a the number B(5, days Can = you see why this is a binomial situation? 0.4) ⎛ 5 ⎞ P( X of bus. 2) = ⎜ ⎝ ⎟ 2 2 3 ( 0.4 ) ( 0.6 ) We require P(X = 2) ⎠ = 10 × 0.16 × = 0.3456 = 0.346 (3 sf) 0.216 Using your GDC: See Chapter Section GDC help on CD: demonstrations Plus and GDCs Example When were of on Alternative for the TI-84 FX-9860GII the CD. administering cured. 10 Casio are 17, 5.12 The a dr ug testing it was program known that 80% administered the of people dr ug to using two it groups patients. Assume What is the probability that all 10 patients were cured in both that X is groups? binomial are two since there outcomes: Answer a Let X be ‘the number of patients Multiply the success and cured in a group of 10’. P(X = 10) is a cure probabilities and P(X = a failure is ‘not 10) a cure’. Assume that 10 P(X = 10) = 0.8 = 0.10737 … because the two events (the patients the 2 [P(X = 10)] trial results (0.10737…) being cured in each group) are patient = 0.0115 (3 sf) independent. So for two groups of to patient the probability all are The cured xed probability 2 is [P(X = 10)] success Probability distributions are 10 independent. patients, from 2 = is 0.8. of Exercise 1 A It D regular is tetrahedron rolled What is four the most downwards? 2 The he shoots the at a he hi ts b he misses factor y produce 4 in a none c at The a a The will one b at The least 6 In a an row 7 In the is is of A b times of bottom that this a one the face red value bull’s red face. is noted. face will end occurring? eye when attempts times at least five times. making four be that a that the any component is type machine 13 of will What from exactly b same 0.01. components each will is the probability machine, be not be faulty faulty? telephone If the lines line is engaged switchboard lines that be at are has 10 at a company lines, find the engaged free Nicole most three hall, it (to goes that is probability on 4 significant to bed five at figures) 7:30 on consecutive a given days day she is goes 0.4. to days. known that, in that a 15% row of of six desks desks, are wobbly . more than wobbly? the six are probability the probability that exactly one will be wobbly in a desks? production Processors packet will the scores eight faulty the on mass defective. a of 0.25. of the will What in probability examination one b is three 7:30 What of probability machines will probability at of and that half Calculate bed be two probability a that five four sample probability color faces 0.55. substandard least white marksman is bull the number the a three Questions switchboard 5 bull the has component. that, that target the Exam-Style A is probability a and likely What probability Find 3 times has is of are selected computer selected at at random. processors random Find the it and is found put into probability that packs that 5% of are 15. it contain i three iii at Two there defective least two packets processors defective are no ii defective processors processors selected at random. Find the probability that are i no ii at iii no defective least two processors defective defective in either processors processors in one packet in either packet packet and at least two in the other. Chapter Example A box red. contains The How least rest many one a are large white. flowers red number car nations Car nations must car nation of be picked among are so them picked that is of which at the one-quarter random from probability greater than that the are box. there is at 0.95? Answer 1 Let X be the random variable ‘the are number X ∼ P(X of B(n, ≥ red red, so P(red) = 0.25 4 car nations’. 0.25) 1) = 1 – P(X = 1 – (0.75) = 0) n n 1 − (0.75) We > 0.95 require P(X ≥ 1) > 0.95 n 0.05 > ( 0 .75) log and 0.05 > 0.75 < n least picked at out least If 2 1% X ∼ X 4 The log 0.75 inequality of the red B(n, of the to least value of n is 11. be ensure there car nation is among 0.95. and a that in 0.2) P(X large can the < box be = of P(X if must ≥ 0.0256, fuses taken sample and 1) 1) > are the be find n faulty . What probability greater 0.75, find than the is that the largest there are 0.5? least possible n probability would How must that than in size fuses scored 5 box 0.6) competition she The E fuses ∼ value negative B(n, of faulty If When 0.05 greater sample 3 n. log probability Exercise 1 for 0.05 car nations one is log > 10.4 11 the them inequality you divide by amount, at is need least many to Anna Find take once times probability Probability that 0.3. is at distributions if least the greater must that scores the an a penalty number probability than one tail in a hockey attempts that a goal that is 0.95. unbiased least goal of coin will be tossed occur is at so that least 0.99? no a the > n that the so n log At Solve n log 0.75 reverses. Expectation of a binomial distribution 2 Think of the example of the biased coin where P(H) = . 3 If you to get toss a the coin 3 times how many times would you expect head? Intuitively the answer This same is 2. 2 is the calculating 3 as 2 The proof of this 3 formula ➔ For the binomial expectation The Galton scientist half, Board, Sir where the poured. ball falls Each time a process heights If the of of distribution why Example A biased The of dice sixes bean one machine, in In directly this p), the the is not standard on level syllabus. consists slots. B(n, np arranged is to hits therefore heaps of heights fur ther on It ∼ where X of an is staggered the middle above the a device upright order , of top the nail for board and top, so statistical with a lower there that evenly is half a experiments spaced divided funnel nails into into a named driven after into number which balls English its upper of can each nail. of the nails, it can bounce right or left probability. number the funnel ball This are = or Galton. nails The equal E(X) rectangular directly with X, quincunx Francis evenly-spaced be of distribution (See gives balls balls of this of the is in rise the to a slots sufciently ball heaps will Section 15.3). Y ou binomial at the large distribution then the approximate may in the bottom. wish to distribution a normal investigate is. dice is is thrown then for thrown these 12 30 a times fur ther and 12 the number times. Find of the sixes seen expected is8. number throws. Answer 8 X ∼ B(12, p) where p 4 = = 30 Let X be ‘the number of sixes seen in 15 12 throws’. 4 E( X ) = np = 12 × = Y ou 3 .2 may wish to 15 conduct your binominal and Exercise a A A fair fair sixes c A how close F coin is tossed 40 times. Find the expected number of the results are expected to binomial results. heads. b experiment explore your 1 own dice is rolled 40 times. Find the expected number of obtained. card is drawn retur ned. repeated 13 40 of from these times. a pack cards Find the of are 52 cards, labeled expected as noted and Hear ts. number of This is Hear ts. Chapter Exam-Style X 2 is a mean A 3 a of each X is variable choice with test each number a the distribution b the mean c the probability 10 100 or of more families numbers of Number of Find b Using two 10 15 one X and ~ p B(n, = 0.4, questions correct p). Given find and answer the n four per that possible question. answers Assume answer. questions answered correctly’ give: X that purely each a by with student will achieve the pass mark of guessing. three children are found to have these girls: girls the three that X Frequency a of of is has only guesses ‘the such distribution one student If 4 the multiple for Questions random 0 1 2 3 13 34 40 13 probability your value children, that from in a a a single baby calculate sample of the 100, bor n is number you would a girl. of families expect to with have girls. Variance of a binomial distribution The Chapter 8 introduced the concept of the variance of a set of data, proof variance a measure of dispersion. not on Level The the ➔ formula formula If X ~ Thinking for the variance of the binomial distribution is given of the as formula the is Standard syllabus. in booklet: B(n, p) about then the Var(X) original = npq where example of q the = p – biased 1 coin where 2 P(H) = , if you toss the coin this will 3 times you expect to get a head 2 times. 3 However, this obviously experiment Using the many formula for times not you = will ever y time. sometimes get npq = 3 × If 0, you 1 repeat and 3 heads. Y ou variance, 2 Variance happen 1 × 3 can by the = 3 taking square 3 The For the binomial distribution where X ~ B (n, of the variance. expectation of X, E(X) = expected X, E(X), variance of X, Var(X) = npq where q = 1 – distributions the also mean, p. so Probability is np called ● value p) of ● σ, 2 general ➔ the deviation, root In nd standard E(X) = . . Example In a large company , 40% of the workers travel to work on public transpor t. A random Find on the sample of expected public 15 workers number transpor t, and of the is selected. workers standard in this sample that travel to work deviation. Answer Let W who be the travel to number work of on n workers = 15, p = 0.4 public transpor t. W ~ B(15, E(W ) = Var(W ) 15 = Standard 3.6 = 0.4) × 15 0.4 × deviation X ~ B Find 1 A the fair An coin the b Var(X) c P(X < in calculate and the the standard npq deviation is square root of mean and variance of X deviation of the binomial 0.6). 40 times. number dice is of Find the mean and standard heads. thrown 10 times. Let X be the number of Find expected number of sixes μ). frequent once , tossed obtained. a A is of Exam-Style 5 Standard is B (12, unbiased sixes np = ⎠ mean deviation 4 = Var(W) 3.6 ⎞ ⎟ 4 distribution 3 = variance 0, ⎜ ⎝ 2 0.6 G ⎛ If E(W) 6 × 1.90(3 sf) Exercise 1 = 0.4 Question flyer ever y 22 occasions. a the 5 finds trips, Using expected that on a she is average. binomial number delayed of One year model, jour neys at a par ticular she uses the air por t air por t on find that will be delayed at that air por t 6 b the variance c the probability At the local can is r un 100 that athletics metres she club, in is delayed the under on expected 13 fewer than number seconds is 4.5 of and 4 occasions. people the that variance 3.15. Find 13 the probability that at least 3 people can r un 100 m in under seconds. Chapter Exam-Style X 7 is a mean of the variable For Find random the Hence variable possible calculate The these P(X foot, a 2 Where 3 Is 4 Join the the histogram 6) the ~ and p variance B (n, n p), and for B (n, = of p). 0.3 Given that the find: X. E(X) = 9.6 and Var(X) = 1.92. p. each normal 50 possible pair. distribution students weight, the in your maximum school hand for span, one of length of of data the roughly from and measurements more peak of 7.8 X wrist. of midpoints symmetrical If of histogram the – height, histogram is ~ that distri bution around circumference Draw Y our from categories: 1 = normal data X values Investigation Collect is the b a . such distribution n a 8 Question random of the the a measurements tops of the investigation cur ve around histogram? symmetrical? is is bell-shaped central were bars of your probably with the histograms with a cur ve. f(x) roughly majority of value. taken, a histogram plotted and the O midpoints become of the more tops of the bars symmetrical and look cur ve joined with a cur ve, it would like the shown. a normal Gaussian normal normal distribution is probably the Friedrich most distribution in statistics, since it is model for many naturally These attributes of include the people, Gauss cur ve In animals mass-produced and plants, the old items from factories. could approximation also be of, for to applied example, times, complete or IQ a as the student is histor y, it ● the is piece of work, scores. work. por trait of probability Gauss played the in Gauss, function the appeared note. an the French impor tant statisticians and role in Abraham Pierre-Simon De were Moivre involved in developed in distribution, the binomial this was not 1733 as discovered much the to about the mean de Laplace an of normal the ear ly cur ve approximation although until his 1924 paper mode and median are the used the normal by cur ve Karl in 1783 describe the distribution of errors, and in 1810 same. proved the distributions Laplace (μ) he Probability the its mathematically to data bell-shaped symmetrical mean, and (1667–1754) Pearson. ● used astronomical exam case cur ve Gauss Carl an on ● analyze 10-Deutschmark (1749–1827) times each “Gaussian The Moivre In the and its distribution reaction called mathematician (1777–1855). to Germany, cur ve Although scores, also physical on even is German occurring normal variables. the a 1809. suitable cur ve after normal impor tant Curve distri bution cur ve” The x would This The is it bell-shaped The until then an Central essential Limit statistical Theorem. theorem called The characteristics There is no single normal of any cur ve, normal but distribution a fami ly of curves , each one Remember that mean, μ, is the and defined by its μ, mean, and standard the σ deviation, measure If a random variable, X, has a normal average, standard σ, deviation, ➔ the distribution with of is a spread. mean 2 μ and standard σ, deviation this is written X ~ N (μ, σ ) Note μ σ and are called the parameters of the that in the 2 distribution. expression X ~ N(μ, σ ), 2 σ The mean is the central point of the distribution and the is the variance. standard Remember deviation describes the spread of the distribution. The higher variance standard deviation, the wider the normal cur ve will that the the is the standard be. deviation squared. f(x) 2 These three graphs show ~ X N (5, 2 x ), x 1 x 2 3 1 2 ~ X N (10, 2 2 ) and X 2 The all ~ N (15, 2 ). 3 standard the width same, μ but deviations so the μ < 1 are cur ves are all the same x 0 μ < 2 5 10 15 20 3 2 These three graphs show X ~ N (5, 1 ), f(x) 1 X 2 ~ X N (5, 2 1 2 ) and X 2 ~ N (5, 3 ). Here the 3 means are all the same and all the cur ves X 2 are centered around this but σ σ < 1 σ < 2 3 X 3 so cur ve is X narrower than X 1 , and X 2 is 2 x 0 narrower than 5 X 10 3 The cur ves deviations The No may but area matter the So equal cur ve in what the to as this they different all have beneath distribution, and have 1. the We area can same and/or of μ σ and under the different standard characteristics. normal therefore representing normal the the values total means distribution are for cur ve consider is a normal always par tial curve probability the areas f(x) same under probabilities. distribution we could find the probability μ x P(X < 5) by finding Unfor tunately cur ve) to for the the the shaded probability nor mal area on the function distribution is (the ver y 0 diagram. equation of complicated 5 the and difficult use. 2 ( X ) 1 f (X ) 2 2 − e ∞ < X < ∞ 2 It would cur ve! be too hard However, for there us are to use other integration methods we to find can areas under this use. Chapter The standard normal distribution Note The μ = to standard 0 σ and describe normal = 1. the The distri bution random number of is the variable standard normal is called deviations distribution Z. It any uses value where ‘z-values’ is P(Z that = think a) of having away the = no the P(a Y ou Z ~ The can standard use N (0, 1) Example Given a no can line and area. mean. This ➔ Y ou as width therefore from 0. this for P(−2 d P(Z < < GDC values distribution to calculate between a is the and b written Z areas and ~ under hence N (0, the P(a < that Z < b) = P(a ≤ Z ≤ b) = P(a < Z ≤ b) = P(a ≤ Z < b) 1) cur ve Z < of b). that a your normal means < Z ~ N (0, Z < 1) 1), 0) find b P(Z < e P(|Z| 1) > c P(Z > −1.5) 0.8) Answers a P(−2 < Z < 1) = 0.819 Using the distribution menu on GDC your GDC, choose nor mCdf and Plus enter the values in this order: help upper limit, mean, standard deviation. b P(Z < 1) = 0.841 Enter the negative lower limit as a ver y small number, 999 –9 c P(Z > −1.5) = 0.933 × 10 Enter the upper limit as a ver y large 999 number, 9 × 10 { Probability distributions Continued on CD: and Casio Alternative for the next page are on TI-84 FX-9860GII lower GDCs limit, on demonstrations the CD. f(Z) d P(Z < 0) = Here 0.5 you do calculator not need because to the use the graph is f(Z symmetrical e P(|Z| > 0.8) = 1 – 0.576 = 0.424 about the < 0) = 0.5 mean. z 0 |Z| > 0.8 –0.8 < Z means < 0.8 See Chapter Section Exercise 1 Given 2 3 4 5 6 Find that < the Z Z ~ < area 1 b between 0.5 the a 1 b 2.4 and area standard Find the 1 b 1.75 area standard Given Z the 1.5 the the deviation N (0, 1) the cur ve the the is the GDC b P(Z > 0.72) d P(Z > −2) e P(Z ≤ −0.28) N (0, 1) < Z < 1.2) that Z ~ N (0, 1) P(0.2 Given P(|Z| a < use the P(−2 b use the 0.4) Z 3) mean the mean. than: than ≤ mean. find c GDC < the from more to 0.65) ~ < cur ve: from less < Z Z mean. P(Z that < mean below the P(−3 c mean that below is a Given 2) deviations above use < normal which above deviations Z deviations cur ve deviations under < standard standard deviation ~ P(−2 standard under standard that 2 and standard a find b under between Find N (0, 1) 1) a a 7 H P(−1 a 17, 5.13. to to c 1.8) P(−1.3 ≤ Z ≤ −0.3) find P(|Z| b ≥ find 0.3) GDC P(Z > 1.24) f(z) 0.4 In Question that Z lies standard of the 1 of within Exercise one deviations mean 15H, standard of the you found deviation mean and the of three probability the mean, standard 0.2 two 0.1 deviations respectively . z –3 Y ou can see that most of the data for a normal –2 –1 0 1 2 3 distribution 68.27% will lie within three standard deviations of the mean. 95.45% 99.73% Chapter Probabilities Clearly , for however, standard normal deviation of 1). other ver y few normal real-life distribution But you can distributions variables (with a mean transform are of any distributed 0 and normal a like the standard distribution 2 X N ( μ, ~ normal in σ ) to the standard distributions location and have normal the same distribution, basic shape because but are all merely shifts spread. 2 To transform z-value on ~ given N (0, 1) value use of the x on X N ( μ, ~ σ ) to its equivalent formula x z Z any = Y ou can then use your GDC to find the required probability . X 2 ➔ If X N ( μ, ~ σ ) then the transformed random variable Z has a standard Example normal distribution. 2 The random variable X ~ N (10, 2 ). Find P(9.1 < X < 10.3) Answer < P(9.1 X < Draw 10.3) a sketch. f(x) P(9.1 < x < 10.3) GDC help on CD: demonstrations Plus and GDCs x 0 5 9.1 z 10 15 10.3 10 z = = < X < of x. < 10.3) Z < 0.15) Enter Check the values that reasonable X <10.3) = 0.233 sketch. value = 0.15 P(−0.45 P(9.1< each 2 0.45 P(9.1 10 Standardize = 2 = 20 Probability distributions the into your answer when GDC. looks compared with your Casio are on Alternative for the TI-84 FX-9860GII the CD. Y ou can directly the is also using the these GDC. standardization the quickest method But it of is Enter of = Without most efcient this to using this question. know the standardization. lower mean and solutions formula, answering impor tant method Exercise nd limit, 10, upper standard limit, deviation = 2. I 2 The 1 random variable X ~ N (14, 5 ). Find P(X a The 2 < 16) random P(X b variable X > ~ 9) P(9 c N (48, ≤ X < 12) P(X d < 14) 81). Find P(X a < 52) P(X b ≥ 42) P(37 c < X < 47) 2 The 3 random variable X ~ N (3.15, 0.02 ). Find P(X a < Example Eggs laid is b P(X ≥ 3.11) c P(3.1 < X < 3.15) by distributed, What 3.2) a chicken with the are mean probability a an egg weighs c an egg is more between known 55 g and to have standard the mass normally deviation 2.5 g. that than 52 and 59 g b an egg is smaller than 53 g 54 g? Answer 2 W ~ N (55, 2.5 ) f(w) Sketch 2 W ~ N(55, 2.5 Mean ) 3 × σ first. = = 55 3 × 2.5 = 7.5 0 w 45 50 55 60 65 Enter the value in your GDC: GDC lower limit, mean = upper limit, help Plus and GDCs P(W > 59) = 0.0548 (3 sf) b P(W < 53) = 0.212 (3 sf) c P(52 < W < 54) = CD: Casio Alternative for the TI-84 FX-9860GII 55, standard a on demonstrations deviation = are on the CD. 2.5 0.230 (3 sf) Chapter Exercise J Exam-Style 1 Questions Households groceries in with distribution what 2 is the less b more c between with a 3.5 mm 3 The and or of known the What 4 Packets 550 g. the The more The with mass the mass that The Here you need a nominal containing find the Y ou value too cut-off can use of little your I rejected. to wait in distributed will have wait breakfast packets What to of are Out Dr. 0.25 mm. smaller of a than batch Barrett’s with wait less than cereal of are ‘Flakey with a propor tion washing powder standard that a chosen the of 500 mean waiting 14 minutes more than 20 10 minutes? said to flakes’ mean of of contain is such that 551.3 g, packets will and contain is normally deviation packet chosen of at distributed 20 g. random has a 150 for GDC a at mass random. which is What less is the than probability 475 g? distribution value For juice. point which normally 475 g. have find deviation any distributed and normal to are distributed minutes. of of are probability . and patients probability packets distribution, mass? 500 g than normal the spending: diameters have that 15 g. packets of a that on doctor. of stated less inverse 4 normally packets all cumulative to of Three b of mean Find a the week acceptable? flakes’ deviation than a are per Assuming follows standard normally production masses standard 5 ‘Flakey a be probability propor tion of with patients the €100 week. 4.5 mm would see of €20. household per and deviation to a bolts be of expenditure of €125 than to deviation accurately time average week 4 mm many an week per and bigger minutes b of standard Find a €90 produces length is per measured how room grocer y €80 mean spend standard €130 than are bolts of than machine Bolts a probability a A Por tugal ml. The the to in the example, 5% of data a cartons owner of minimum help find that has company the are given cartons rejected company volume this a fills of value. a of juice for may wish to carton. The calculator See has a function called Inverse Normal which will do this. In Chapter Section examples Z ~ we will retur n N (0, 1) Probability distributions to the standard normal 17, these distribution 5.14. Example Given a that P(Z < Z a) ~ = N (0, 1) use 0.877 b your P(Z GDC > a) to = find 0.2 a c P(−a < Z < a) = 0.42 Answers a f(z) Draw a sketch. 0.877 a 0 z GDC help on CD: demonstrations Plus and GDCs P(Z a = < a) = 1.16 Casio are on Alternative for the TI-84 FX-9860GII the CD. 0.877 (3 sf) Notice b that to find the value of a f(z) f(z) for P(z < a) = P(Z easily 0.8 > a) find P(Z < a) The areas a = = 0.2 you can more for 0.8 0.8 0.2 0 P(Z a c > = a) = a 0 z 0.2 P(Z < a) = a z 0.8 0.842 (3 sf) P(−a < Z < a) = 0.42 either side of f(z) the shaded size 0.42 and region equal are the same to 1 (1 − 0.42) = 0.29. Hence 2 P(Z –a a < a) = 1 0.29 = 0.71 z 0 a = 0.533 (3 sf) Chapter Exercise Find 1 a < a) = c P(Z > a) = a such 0.922 < Z < a) c P(a < Z < −0.3) a such Find < the > a) b P(a b P(|Z| = 0.342 = 0.12 = < Z < 1.6) = 0.787 0.182 that: Z < a) values a P(Z that: P(1 P(−a b 0.005 a a 4 that: P(Z Find 3 such a Find 2 K = of 0.3 a shown in these > a) = 0.1096 diagrams: b f(z) f(z) 0.95 0.2 z –5 0 z 5 –3 –2 –1 0 1 2 a a Once again, however, distributions Example that are we not 3 are the more likely standard to be normal dealing with distribution. 2 Given that X ~ N(15, 3 ) determine x where P(X < x) = 0.75 sketch to show Answer f(x) Draw a the value of x required. 0.75 x 0 x 15 This question is best done on the GDC help on CD: demonstrations GDC. In invNor m enter x, Plus standard x = z = deviation. You could also by first standardizing { answer the question 15 3 Probability distributions and GDCs 17.0 x the value Continued Alternative for the TI-84 mean, on of x. next page Casio are on FX-9860GII the CD. P (X < ⎜ = x ⎛ P x) 15 ⎞ < Z = 0 ⎟ 3 ⎝ x 0.75 75 ⎠ 15 = 0 6745 3 x = 17 0 Example Car tons with 5% a of Find of juice mean of car tons the contain are are it is to that and rejected minimum if such 150 ml be a for volume, their volumes standard containing to the are deviation too nearest normally of little ml, that distributed 5 ml. juice. a car ton must accepted. Answer Let V be the volume of a car ton. Let m be the minimum volume that 2 V ~ P (V N(150, < m) 5 = ) a car ton must have to be accepted. 0.05 Draw a sketch. f(V) 0.05 m 0 V 150 GDC help on CD: demonstrations Plus and GDCs The the minimum nearest volume is 142 ml Casio are on Alternative for the TI-84 FX-9860GII the CD. to ml. Chapter Exercise L 2 1 X ~ N(5.5, 0.2 ) and P(X > a) = 0.235 Find the value of a 1 of 2 The mass, M, of a randomly chosen tin of dog food is such that less 2 M ~ N(420, 10 ). the values are 4 than the rst Find quar tile. the a first quar tile Exam-Style 3 contain has a into normal An a percentile. a countr y 500 ml must for bottle have filling with a insist that at all least bottles, standard mineral that which bottles amount. puts deviation an of that claim ‘Yummy average 1.6 ml of and Cola’ 502 ml follows a distribution. inspector What What b in machine each 90th Question Regulations to the b is the randomly probability proportion of selects that bottles it a bottle will will of break contain ‘Yummy the Cola’. regulations? between 500 ml and 505 ml? 95% c a 4 The a If 5 a marks standard If 5% by If b Y ou of 550 g chosen 500 the of the d at with of 15 of hypermarket standard and by a and mean. b ml are the liquid are a normally deviation find of What of where and b? distributed 25 g. probability that its 570 g. 10% in of an mean the lettuces. examination of 55 marks are and a marks. or obtain more, fail by a distinction find the scoring f value marks of or d less, f given σ a ml the random, candidates marks (if a and 520 g students be about at candidates value mean between exceeded deviation of sold between of also the is mass scoring may either lettuce distributed 10% find contain symmetrical mass lies the normally a of lettuce Find The are mean mass b bottles b masses with a of and cumulative is known) or probabilities the standard and asked deviation to (if find μ is Extension material Worksheet 15 distribution known) or both. Sacks of loader. Use this potatoes In a test it with was information mean found to find weight that the 5 kg 10% of standard are packed bags were deviation by an over of automatic 5.2 kg. the process. Answer Let M be the mass of potatoes in a 10% (0.1) of bags were over 5.2 kg. sack. 2 M ~ N(5, σ ) { Probability as approximation distribution Example - distributions Continued on next page on CD: Normal an to a binomial P(M > 5.2) = 0.1 Draw f(m) a sketch. 0.1 0 m 5.2 5 5.2 5 0.2 Standardize. Z = 0.2 P Z 0.2 P or 0.1 Z 0.9 From P(Z the < GDC 1.28155 . . .) = 0.9 GDC help on CD: demonstrations Plus and GDCs Casio are on Alternative for the TI-84 FX-9860GII the CD. 0.2 = 1.28155.... σ σ = 0.156 Example A (3 sf) manufacturer she is under 5.5% does producing. 1.8 cm as too in big. not know However diameter. What is a It the the mean sieving is found mean and system that and standard rejects 8% of standard all the deviation ball ball of bearings bearings deviation of the the diameters larger are than rejected ball as bearings of 2.4 cm too ball bearings and small those and produced? Answer Let D be the diameters of ball bearings produced. We know that 8% are too small, and 5.5% are too 2 D ~ N(μ, σ ) big. P(D < 1.8) = 0.08 P(D > 2.4) = 0.055 Draw f(d) a sketch. 0.08 0.055 0 1.8 2.4 1.8 2.4 and Standardize 1.8 Z each value. P d < = 0.08 From the first expression. { Continued on next Chapter page Z > Z the second expression. 2.4 P From = 0.055 or 2.4 P < 1 = 0.945 0.005 = 0.945 From the GDC we P(Z < −1.40507 P(Z < 1.59819 know . . .) . . .) = = that 0.08 and 0.945 1.8 = 1.40507 . . . Solve and simultaneously for μ and σ. GDC 2.4 = 1.59819 . . . help on CD: demonstrations Alternative for the TI-84 Plus and GDCs μ = 2.08 σ and Exercise = Casio are FX-9860GII on the of σ CD. 0.200 M 2 1 X ~ N(30, σ 2 X ~ N(μ, 4 3 X ~ N(μ, ) and P(X > 40) = 0.115. Find the value 2 ) and P(X < 20.5) = 0.9. Find the value of μ 2 P(X 4 A < σ 41.82) random Exam-Style The mean children Given = that 0.0287, variable σ, deviation 5 ). such X > μ find is that P(X 58.39) P(X < 89) 0.0217 and σ and normally = distributed = 0.90 and with P(X mean < 94) μ = and standard 0.95. Find μ and σ Questions height have a of children height of of a 145 cm cer tain or age more. is Find 136 cm. the 12% Lamber t Adolphe Jacques Quételet of standard (1796–1874), deviation 6 The of the standard deviation of masses of loaves of bread is mass of 20 g. Only Flemish scientist, was rst the loaves weigh less than 500 g. Find the mean the the normal loaves. distribution 7 The masses of cauliflowers are normally distributed to 1% apply of a heights. with to human mean characteristics. 0.85 kg. 74% of cauliflowers a the standard deviation b the percentage of have of mass less cauliflowers’ cauliflowers with than 1.1 kg. Find: He masses mass noted characteristics greater than 1 kg. as height, strength 8 The lengths of nails are normally distributed that were mean μ with distributed. and standard than 9 A 68 cm roll 35% of of a find rolls Probability are paper of normal the wrapping wrapping lengths deviation rolls value paper over is of 7 cm. 3 m 2.9 m. sold long Find wrapping distribution. distributions 2.5% of the nails measure more μ of is If as and the ‘3 m that the value paper, long’. of It is average the assuming found length standard that that the of actually the rolls deviation lengths of of rolls only of the follow such weight, and normally Exam-Style 10 It is suspected score less Find a Questions that than the the 108 scores marks mean and in on a the standard test test, are normally and 20% deviation of distributed. score the more scores, if 30% than 154 they are of students marks. normally distributed. 60% b of appear scores 11 Due a to students to are randomly in chosen given exceeding Exam-Style table than distributed ball of Find 95% and wool the of 99% 117 consistent as manufacturing, that 495 m Review The normally distribution. deviation more reasonably variations normal 1 be score mean balls have with be length idea of modeled and of the Does this that fact the above? the can marks. by in a standard wool lengths wool have lengths exceeding 490 m. exercise Questions shows the probability distribution of a x discrete a b 2 Find In the by Find a of P(X a P(X value of distribution = x) value = of player −2 cx(6 a x), discrete x = 1, Find b a = x) The Find the 4 A game The probability involves other number Let probability P is on be a Write b Find biased c What d A is is all his son Monday the random 2, 3, 4, tetrahedral 10 total will Exam-Style each then the score two 2, the score of six spinners. 4, 4. Each he 2 k k 0.1 0.1 variable X is 5. (four-faced) is after One 1 2 3 1 1 1 4 4 8 4 shown. is spinner of each value week If by the £10. expect on values value of determines gets boy numbers possible expected mor ning. than 2 E(X). possible total 2, of mathematician give a 1 two rolls. numbered is spun Probability 1, once 2, 3, and x 4. the recorded. probability the each spinning product down the of numbered each the of 1 0.3 Score dice. 0 X of − c. rolls −1 X k. expected the game variable value probability defined 3 the Find The a random for P of P amount him spins get to and Otherwise to spinners P? the getting son the after pocket play the he 10 of the game product gets £5. weeks of money is How to on greater much playing the in game? Question 1 5 In a train, of the passengers are listening to music. Five passengers are chosen 3 at random. Find the probability that exactly three are listening to music. Chapter 6 When is that 7 a 0.1. Let he X boy He wins. be Given that P(X Given that P(65 dice be Copy b are is but the like eight much 3 > mean a), and the Find value P(X > of If a 1 of or neither X, a 6 is rolled rolled you the ‘the is will table you win of $5. the dollars won in a would you expect 9 ii to gain (or lose) of the at songs on my friends MP3 player. If probability that I like at three songs. probability school random ii more the c How large one four than Find throwing most the of mean Find a the the the Probability of a of I choose least three sixes twice in five throws 71. a be is of be taken. Find left-handed be greater the the probability than that a) a group must a of of the that sample it of contains 10 at people. least mean 0 and variance 1. 0.85. scores are of normally less than distributed 80. scores. more student with students have the score = in 0.95? P(|Z| ≤ people probability variable students that if random deviation probability left-handed. left-handed. to to of student is is sample that given 85% distributions people normal such test five number person a in left-handed random standard test 10 be will likely must value results Find of will standardized the person half left-handed To pass b of sample exactly b a game’. Question i a you dice. large with dice game. random the The three the games? find Find these play in b is on 1 songs Z 5. probability three A E(X). deviation Y ou exactly a prizes $1? showing number pay like In prize a somewhere will I the a of a). that six wins find standard probability Find he number independent, 75 find 0.954, that total the one = are the find a 6 games with P(X probability denote Question songs Exam-Style 5 the a) the Let X a of 4 = < game 30% fair, x) = Exam-Style I if −5 1 i X probability x How that 65) < complete distribution c < thrown. $1, and P(X a exercise paid What a at twice. distributed b Three game game Assuming a will 2 a the normally Review 1 plays plays than chosen at 65. random passes the test. Exam-Style 7 The lifespans 15% of hours. 8 The Questions Find time the last less mean taken for with a batteries than and 30 to of μ normally hours standard Samuel mean are get and 10% deviation to school minutes and distributed. of of a is batteries the each It last lifespans mor ning standard is found of that more the than 50 batteries. normally deviation of minutes. 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Chapter Exploration CHAPTER As par t which This and of will a tips topic . The 10 ● be to Mathematics assessed gives help the and you getting is an should of aim to class Discussing the to SL get a on good on grade as your 20% by need of your your as Discussing sure Discussing that for you to interests exploration, grade. your hints exploration on choosing show that you can you. spend: time 10 assessment suitable your an exploration. ● criteria hours ● topics/titles progress with your teacher ● of Planning your your select and/or Applying ■ time exploration, doing appropriate collecting research to topic and organising your information mathematical Ensuring are own an Researching , data ● nal suggestions help ● write exploration, making well to exploration oppor tunity area as you planning criteria, the an course, counts advice star ted About mathematics hours you and assessment exploration apply Y ou your chapter satises OBJECTIVES: that derived all of using processes: your results logical deductive reasoning ■ Ensuring that necessar y) ● Demonstrating Checking ■ Adding and that terminology proofs coherent (when and correct mathematical communication ■ your are presentation: your are notation and consistently diagrams, graphs or correct char ts where necessar y ■ Making sure structured Exploration your and exploration reads well is clear ly Y our school will set you deadlines for submitting a draft and the Ever y final piece of candidate work. taking If you do not submit an exploration then you receive a grade of “N” SL Mathematics must submit an exploration. for Mathematics SL, which means you will not receive your IB Ensure that you diploma. know your deadlines . Y our Internal exploration will be assessment assessed by your to cri teria teacher, against school’ s and keep them. given criteria. It will then be assessment The final exter nally moderated by the IB using the same criteria. mark for each exploration is the sum of the scores for each criterion. These The maximum possible final mark is criteria explained This is 20% of your final grade for Mathematics good your The exploration peers, and criteria are should be clear self-explanator y split into five all areas, and the A easily way to understood by one of through. how A with E: to sure Mathematical Criterion C Personal your satises you understand criteria B ensure on them. Communication Criterion more tips exploration Make Criterion in SL. detail, A are 20. and these consult presentation them frequently engagement when Criterion D Reection Criterion E Use writing your exploration. Criterion A: This assesses criterion completeness Achievement of of mathematics Communication the level the organization, coherence, conciseness and exploration. Descriptor The exploration does not reach the standard 0 described 1 by the descriptors below. The exploration has some coherence. The exploration has some coherence and 2 shows The some organization. exploration is coherent and is coherent, well 3 organized. The exploration well organized, 4 concise and complete. Chapter Y our To get A exploration a good well mark organized An A rationale A description A conclusion A Y our Any graphs, A concise A complete It is tables that should of the logically ‘read is be one is an discuss the explanation exploration developed context of which and why to the you should easy of exploration chose be this clearly topic identiable follow. well’. diagrams not have include that you attached that one references exploration from a in in as focuses which all use should accompany appendices on the steps aim are to the and avoids clear ly the work in the document. irrelevancies. explained without detracting the B: This assesses criterion are cited contain a footnotes formula should end. contain List any a from appropriate, as a i.e., appropriate. mathematics to what extent mathematical bibliography books Mathematical appropriate where For example, book, etc., if put you the are using source of footnote. exploration at should publication, a Criterion use is exploration appendix ● aim and and exploration quote Y our the Communication conciseness. quote the you should should place essential Y our of A: should which exploration appropriate in which exploration its Criterion exploration introduction coherent from for you use, as any appropriate. websites This you can be consult, in an etc. presentation you are language able to: (notation, symbols, terminology) ● define ● use key terms, multiple diagrams, Achievement where forms tables, level of required mathematical char ts, graphs and representation such models, appropriate. where as formulae, Descriptor The exploration does not reach the standard described 0 by Exploration the descriptors is some below. 1 There appropriate mathematical presentation. 2 The mathematical presentation is mostly 3 The mathematical presentation is appropriate appropriate. throughout. a Y our To get exploration a Y ou good are mark expected communicating Y ou are for Criterion to use calculators, software, appropriate, Y ou should dene Y ou should express Y ou should always Variables Do key where to scales language and when ndings. appropriate spreadsheets, enhance results include reasoning use software, to terms, your and communication mathematical ideas, choose mathematical as appropriate to Mathematical appropriate mathematical encouraged B: ICT tools such databases, mathematical as graphic drawing and display word-processing communication. required. an and appropriate labels if degree you use a of accuracy, graph. when T ables appropriate. should have headings. should be explicitly dened. x not use use 0.028 calculator and not Criterion C: This assesses criterion exploration and Achievement or computer For example, use 2 and not 2^x; use × not *; 2.8E-2. Personal make notation. the it engagement extent your to which you engage with the own. Descriptor level The exploration does not reach the standard 0 described There is by the descriptors evidence of limited below. or supercial 1 personal There is engagement. evidence of some personal of signicant 2 engagement. There is evidence personal 3 engagement. There is abundant evidence of outstanding 4 personal engagement. Chapter Y our To get a Y ou will exploration good mark should be Y ou choose easier can for to Criterion a topic display demonstrate attributes and skills. These Thinking and Thinking creatively Addressing Presenting Asking Looking Considering Exploring working and D: This assesses criterion creating historical Criterion that you are interested in as it engagement by using some of the following different interests ideas making unfamiliar exploration engagement. independently mathematical for engagement include: personal questions, Personal your personal personal your for C: in your conjectures mathematical and global own and way investigating models for mathematical real-wor ld ideas situations perspectives mathematics. Reflection how you review , analyze and evaluate the exploration. Achievement level Descriptor The exploration does not reach the standard described 0 by Y our To get a below. 1 There is evidence of limited 2 There is evidence of meaningful 3 There is substantial good Although Y ou descriptors or evidence supercial of reection. reection. critical reection. exploration also the be can mark reection found show Criterion may be throughout reection Discussing Considering Stating Making Exploration for the to your limitations different in the conclusion exploration of signicance possible Reection to the exploration, exploration. implications the links seen the in D: of your elds results your and/or by ndings and extensions and/or areas of to results your results mathematics. it may Criterion E: This assesses criterion Use of to mathematics what extent you use mathematics in your exploration. Achievement Descriptor level The exploration does not reach the standard described 0 by 1 the descriptors Some relevant Some relevant below. mathematics is used. mathematics is used. Limited 2 understanding Relevant 3 of the is demonstrated. mathematics course is commensurate used. Limited with the understanding level is demonstrated. Relevant of the mathematics course is commensurate used. The with mathematics the level explored is 4 par tially are correct. knowledge and understanding demonstrated. Relevant of Some the mathematics course is used. commensurate The with mathematics the level explored is 5 mostly are correct. Relevant of Good knowledge and understanding demonstrated. the mathematics course is used. commensurate The with mathematics the level explored is 6 correct. Thorough knowledge and understanding are demonstrated. Y our To get exploration a Y ou good are course the Y ou If Y ou you should the you for expected are syllabus, listed mark in the need at prior of only to produce studying. or a ensure level can to Criterion that the of that mathematics is commensurate mathematics level (or you explore with the should level either of be the par t of beyond). mathematics involved is not completely based on mathematics learning. mathematics get a is maximum demonstrate mathematics Use work The similar E: that not of commensurate two within marks your for wi th this exploration the level of the course cri terion. that you fully understand the used. Chapter . 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Honesty Y our This is extremely impor tant in all your work. Make sure teacher Diploma you have read and are familiar with the IB Academic or IB that Programme Honesty coordinator will be document. able to give document. Academic Honesty means: ● that your work is authentic ● that your work is your ● that you conduct ● that any work Authentic ● is ● can work and ● based (e.g. use oral must on on the your your work (e.g. own properly another in proper ty written source is examinations properly cited. a Exploration in own and original ideas footnotes language of ideas others, and and a but this must all sources expression bibliography). fully be fully bibliography) – for both assignments acknowledge in from intellectual work: draw must yourself taken acknowledged ● own and appropriately written you this Malpractice The IB defines malpractice as ‘behavior that results in, or may ‘Plagiarism’ result in, the candidate or any other candidate gaining an derived advantage in one or more assessment from ● plagiarism ● collusion else – – working write an your duplication ● any other of to ● All subject ● Candidates academic Schools secretly at advantage. that and gains policy must areas must published least This one other includes passing it or off as otherwise person having your in someone own an unfair advantage. must be in place to promote clearly must be understand promote clearly the aware this policy policy of the penalties for dishonesty must enforce Acknowledging to with work, Honesty candidates penalties, if incurred. sources acknowledge all your sources. Both teachers and Y ou moderators can usually tell when a project has been will nd schools use computer software to check for plagiarism. If found guilty is of diploma. It . Record Throughout not plagiarism the wor th course, then taking the you will not receive your the jour nal, help you to keeping it would either focus be a good idea to keep an manually or online. Keeping a your search for a topic, and also deadlines. a journal jour nal remind you write you your of document. risk. while will plagiarism Academic Honesty Keeping exploration of you in are a plagiarised. denition Many kidnap’. schools: All Remember ‘to work ● ● others’ exploration, school-wide Academic from undue behavior Advice A copying gain ● ● word includes: Malpractice to a Latin, components’. meaning order is unfair will to exploration also help you demonstrate academic its honesty. 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Y ou need is there The to more your help teacher can Choosing to choose a you focused topic give a that – your so do not questions be afraid are, the to ask for better you. topic interests you, because then you will Y our enjoy working on exploration, and engagement more teacher before exploration. your you you exploration, will be able effectively . put too to Y ou much you will put more demonstrate should time authentic discuss and effor t effor t the into topic into the personal with writing your your give of teacher your stimuli areas you they you general which nd a encourage your based on and own your level mathematical competence. Exploration set choose might interests a Alternatively to topic of – from could topic. might class Each chapter which These could of this be book star ting questions may suggests points help for you to some you find to a ideas topic for ● What areas of the syllabus am I enjoying ● What areas of the syllabus am I performing ● Which are my ● Do ● Have I mathematical prefer I pure ● What is ● career impor tant What mathematics, discovered, mathematical are in my mathematics either areas do I this or outside of topic. your exploration: most? best in? problems reading the want the explorations, a strengths? applied through eventually own in skills for choose or syllabus to enter, the that and I and modeling? media, find what interesting? mathematics field? special these interests or hobbies? Where is the areas? Chapter Mind One map way interest ideas The of and on to spread create a map below suggestions of disease, a topic mind applications mind lead choosing of This how the explorations Cycles: star t Past and or with can mathematics earthquakes Sunspot to map. shows for is to lead into general to area some of interesting explore. broad global a topic such ‘Geography’ diverse topics as can the warming. Future P r e di c t 50 ion s 19 18 00 rebmuN 1 Sp read 3 of 0 dis e a se 150 topsnuS P o pul 100 Dyn amic a tio n s System 5 50 Chaos 0 1940 1960 1980 000 ry eo Th 00 hparG soahC Comparative study of of emission gases Glob al Temperature Change in greenhouse-gas 1990-006, 60 Spain W ar mi differences ng re he osp Atm emissions, % 40 0 - 0 + 0 40 60 Differences in ozone at tr cen con s on Portugal Australia Greece Ireland G lo b a l W a Cananda United States r i n g P Finland r Italy c id e Japan Netherlands it France Sweden s n o Britain Germany Poland Russia Ukraine Estonia Latvia Exploration How c o lo pr r ob em it Fractal was dimensions coastlines u F Le n gt hs of proven and of borders borde rs s p M T i a m e Origin z o n es and development o Calendars International E u c li d ia n time zones and GMT Geometry Gradient grids B rid g es GEOGRAPHY En vir onm ent S k ys c r D a m s seismogram recording the an d rs ar ti fic ial lak es tremor D r i f t n e n t la oC tn A ap e E o n t in e n ta a r t h q u ak es an d t he Rich te r Scale Volcano D r i ft V ol ca no es Chapter . Once Getting you research. of your Do not have have The These pur pose your of topic, the the research next step is determine to is to do some the suitability topic. limit books variety chosen started of your on What ● Which areas of to mathematics different questions ● research that help you are to mathematics these inter net. Y our interesting school and librar y related to will a fields. will of the areas are decide are if your contained accessible to me chosen in or my are topic is suitable. topic? par t of the syllabus? ● Is there lear n in capable mathematics order of Can I show ● Can I limit If I choose your out or work this narrow the syllabus that exploration I would have successfully? to Am I engagement to the in my topic, recommended and length how? of 6 to 12 pages topic? choice another, the this? personal my original suggested complete doing ● if to outside of topic better down is topic? your topic not suitable, Otherwise, to make it has could more your you research either suitable for widen the exploration? Once you think you have a workable topic, write a brief outline covering: ● why you ● how your ● the chose topic the key shapes, ● the cur ve areas fitting, mathematical functions, Exploration to calculus, mathematical integration, topic relates mathematical trigonometr y , ● this in your modeling skills topic, probability concepts operations etc. mathematics you with in your data, will e.g. and algebra, statistics, topic, e.g. geometr y , etc. areas of irregular etc. need, complex e.g. writing numbers, formal graphing proofs, piecewise ● any ● possible mathematics outside the syllabus that you will need Make technology and software that can help in the design keep your exploration and in doing the sure ever y key mathematical your terminology and notation required in teacher topic. In this you are Remember to read your and ready that are your star t fellow understand classmates which to to unclear, read so writing students your your you the topic (your exploration. work can and improve in your way , you will feedback in detail. peers) Y ou that assigns. receive Now internal mathematics deadline ● you of should could comment on ask any be able one of par ts time for able to you to be your exploration complete successfully . them. Chapter Using a graphic display calculator CHAPTER This chapter OBJECTIVES: shows you how to use your graphic display GDC instructions on CD: The instructions in this chapter calculator (GDC) to solve the different types of problems that are you will meet in your course. Y ou should not work through for the techniques whole of the chapter – it is simply here for reference purposes. and the you chapters, GDC if are you you Chapter 1 working can need on refer problems to this the chapter for extra information a 1.3 Finding the (slope) of Simultaneous Solving Solving linear Quadratic functions about the 572 graph zero a 572 573 equations graphically equations Solving 1.8 Finding a quadratic a Drawing local Drawing an equations 1.14 Degrees 1.15 Drawing inverse 585 function logarithmic 585 graph 588 functions and radians 589 trigonometric 590 complicated Solving a functions combined quadratic and equation 591 point sinusoidal Using transformations model Using 2 Dierential Finding 584 a to function model 592 to 594 an function 596 calculus gradients, maximum regression quadratic sliders exponential 579 horizontal calculator Using 1.18 1.19 exponential display a 1.17 578 583 a an exponential minimum asymptote graphic Finding 1.13 logarithms Modeling graph a 1.12 576 functions Finding Evaluating 1.16 quadratic maximum Exponential Using are CD. functions 1.11 More 574 577 1.7 1.10 the graphs functions graph 1.9 TI-84 Plus your Trigonometric gradient line simultaneous Drawing or with simultaneous equations 1.6 help Logari thmic linear Finding 1.5 on the FX-9860GII it. 1.2 1.4 using model. same contents Graphing Finding the mathematical Functions 1.1 in for Casio available When TI-Nspire Instructions the and 2.1 Finding 2.2 Drawing tangents minimum the a points gradient tangent and at to a a point cur ve 598 599 2.3 Finding maximum minimum and points 600 diagram Derivatives Finding a numerical derivative 2.5 Graphing a 602 3 Integral 3.1 the second Calculating 4 the Finding area cur ve a 4.2 Calculating the and lists Entering data frequency Drawing a Drawing from a Before enter frequency you should Important a frequency The ● Opening ● binomial of probabi li ties Calculating binomial probabilities normal X-values normal probabilities diagrams, and correlation Scatter 5.15 Data 613 & Scatter 5.16 Graphs 614 probabilities 624 Scatter the 622 probabi li ties X-values Calculating from 621 normal Calculating 5.14 histogram nCr linear 625 regression coecient diagrams Statistics diagrams using a page using 627 a page 629 start on the keyboard: On menu Off , esc , tab , ctrl , Moving ● Panning ● Change ● Using zoom ● Using trace ● Setting screen new documents, between and pages grabbing window the 620 del ● home statistics know: keys , 618 5.12 612 table table interquar tile Calculating a list the 610 612 a 617 list Use frequency from a 619 Using 5.13 table frequency from 5.11 between data from 616 608 charts histogram shift of table range from Entering Y ou a Calculating 5.10 probabi li ty 5.2 5.4 angle frequency statistics statistics data 5.1 5.3 product a 614 whisker statistics 607 vectors Statistics Drawing scalar from list and Calculating Calculating Calculating a box Calculating 5.9 a a whisker 5.8 606 under from and 5.7 an integral the box 605 Vectors Entering ● of a 603 from value 4.1 two 5 derivative calculus Finding indefinite 3.2 diagram numerical derivative Using Drawing 5.6 2.4 2.6 Drawing 5.5 a in a of in new pages, changing settings document to a change Graphs Graphs Graphs number a axes settings tools in in adding a window in a Graphs page page page page significant figures or decimal places Chapter Functions . Graphing Example Draw Open the a graph new entr y The default the The Type The on 2x y function and displayed axes 1 graph the the type ‘f1(x)=’ ≤ + is graph form ≤ of document line default −6.67 functions The so linear is are is add at a the = 2x + 1 Graphs bottom page. of the work area. Function, displayed. −10 ≤ x ≤ 10 and 6.67. and of y press = 2x enter + 1 is now displayed and labeled screen. Finding information Y our can GDC function, gradient . y such give as you the a lot about of the information coordinates of points graph about of the interest graph and of a the (slope). Finding a zero At The x-intercept Example Find First the known as a zero of the the the of y = graph 2x of + Using a y = 0. y 1 = 2x + 1 (see Example 1). { x-intercept, function. zero draw is graphic display calculator Continued on next page 6:Analyze menu Graph | 1:Zero enter To find the bounds The of zero a GDC you region shows need that a line to give includes and asks the the lower and upper zero. you to set the lower bound. Move the the left Click The the Use the When The .3 the touchpad and choose a position to touchpad. shows another touchpad the the display Click using zero. line and asks you to set the bound. between = the GDC upper y line of the + move and contains word the lower ‘zero’ in the a line so bounds zero, that the region contains the the calculator zero. will box. touchpad. GDC 2x region the to upper 1 displays at the Finding the point the zero of (−0.5, the function 0). gradient (slope) of a line dy The correct mathematical notation for gradient (slope) is , dx and this is how Example Find First the the denotes gradient. gradient draw GDC the of graph y = of y 2x + = 2x 1 + 1 (see Example 1). { Continued on next Chapter page dy Press menu Press enter 6:Analyze Graph | 5: dx Use the Click The touchpad the The Move This = of the again. y you the hand point confirms + line at (slope) open-hand The 2x selected the gradient With select a point on the line. touchpad. point gradient to 1 at is showing, grasping the line on the using gradient point Simultaneous together with the point. symbol the displayed 2. now ever y now that is along that is click the (slope) the line the touchpad point. is touchpad. of 2. equations For . Solving simultaneous equations graphically solving simultaneous equations To solve simultaneous equations graphically you draw the using non-graphical lines and then find their point of intersection. The coordinates point of Example Use 2x x a y = 10 – y = 2 give you the solutions x and rewrite method both to solve equations in the the simultaneous + y = form ‘y =’ 10 x – y = = 10 – 2x GDC will only draw the y = 2 – x y = x – 2 are function a expressed of different before x. If the form, using explicitly, ‘y equations you your need GDC to Using a graphic display calculator to =’ of are as functions a written rearrange solve { graphs 2 that y 1.5. equations The 2x section y graphical + First intersection method, of see the a straight in them them. Continued on next page To draw Open a the graphs new The entr y The default y = document line is 10 – and displayed graph type is 2x and add at a the y = x – Graphs bottom Function, so page. of the 2: the work form area. ‘f1(x)=’ is displayed. The default Type The f1(x) Use – = 10 the are − ≤ x ≤ 10 and −6.67 ≤ y ≤ 6.67. enter displays the first straight-line graph: 2x touchpad cor ner will −10 2x calculator hand This 10 axes of open to the the click on the arrows in the bottom left- screen. entr y line again. This time ‘f 2(x)=’ is displayed. Type The x – 2 and GDC f1(x) = 10 f2(x) = x now – – press enter displays both straight-line graphs: 2x 2 6:Analyze menu Graph | 4:Intersection Point(s) enter To find upper The the bounds GDC bound. to the of shows Move position Click intersection the the a a region line line left you of that and using the need to give includes asks the you to the the set touchpad lower and intersection. the and lower choose a intersection. touchpad. { Continued on next Chapter page The GDC shows another line and asks you to set the upper bound. Use the touchpad between the to upper move and the lower line so bounds that the region contains the intersection. When will Click The region the the The at contains word the intersection, ‘intersection’ in a the calculator box. touchpad. calculator lines .5 the display the displays point solution is x Solving (4, = the intersection of the two straight 2). 4, y = 2. simultaneous linear equations Y ou the be When solving simultaneous equations in an examination, you do not need do not written any method of solution. Y ou should simply write out the equations correct form and then give the solutions. The GDC will do all the use the linear wor king equation for any format in to the in to to par ticular show need equations solver , as you. long as linear, they that are is, both neither 2 Example Solve 2x x the y = 10 – y = 2 a Press contains or order higher x terms. equations: + Open equation new menu document 3:Algebra and | add 2:Solve a Calculator Systems of page. 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