8 Department of Education National Capital Region S CHOOLS DIVIS ION OFFICE MARIK INA CITY MATHEMATICS Quarter 1: Module 1 Introduction to Factoring Polynomials Writer: John Anthony P. Santos Cover Illustrator: Joel J. Estudillo 1 DISCIPLINE • GOOD TASTE • EXCELLENCE What I Need to Know Hello Grade 8 learners! In this module you will learn how to: • factor completely different types of polynomials (polynomials with common monomial factor, difference of two squares). M8AL-Ia-b-1 You can say that you have understood the lesson in this module if you can: 1. 2. 3. 4. find the greatest common factor of a given number. identify prime factors of polynomials. factor polynomials by finding common monomial factor. factor difference of two squares. What I Know Choose the letter that correspond to the correct answer. 1. Find the greatest common factor of 24, 64, 108. A. 2 B. 4 C. 8 D. 24 2. What is the greatest common factor of the monomials a3b3 and a2b5? A. a2b3 B. a2b5 C. a3b3 D. a3b5 3. What is the greatest common factor of the polynomial 30w 3 + 48w + 12w2? B. 6w3 A. 6w D. 12w3 C. 12w 4. What is the factored form of 56a3 – 8a? A. 8a (7a3 – a) B. 8a2 (35a2 – a) C. 8a (7a2 – 1) D. 8a2 (56a3 – 8a) 5. Complete the factor of 7x2y5 + 56x2y4 = 7x2y4 ( ______ ). A. y + 8 B. 7y + 8x C. y + 8x2 D. x2y + 8 C. 484 D. 49 6. Multiply (25 – 7) (25 + 7). A. 625 B. 576 7. Which of the following polynomials can be factored using the difference of two squares formula? A. x2 + 16 B. 25 – y2 C. x3 + 1 D. x3 – 27 1 DISCIPLINE • GOOD TASTE • EXCELLENCE 8. When factored, the expression 16x2 – 25y2 is equivalent to __. A. (4x – 5y) (4x + 5y) C. (4x – 5y) (4x - 5y) B. (8x – 5y) (8x + 5y) D. (8x – 5y) (8x - 5y) 9. Factor 16x2 – 100. A. (2x – 5) (2x + 5) C. 4(2x – 5) (2x + 5) B. 4(2x – 10) (2x + 10) D. 4(4x – 5) (4x + 5) 10. Factor x4 – y4 completely. A. (x2 – y2) (x2 – y2) C. (x – y) (x + y) (x2 + y2) B. (x2 – y2) (x2 + y2) D. (x – y) (x + y) (x2 - y2) Lesson 1. POLYNOMIALS WITH COMMON MONOMIAL FACTOR What’s In When you were in elementary, you have already learned about factoring. A. Find the GCF of the following numbers by making a list. 1. 18 and 36 GCF: ______ 4. 16, 40 and 56 GCF: ______ 2. 30 and 42 GCF: ______ 5. 42, 49 and 70 GCF: ______ 3. 42 and 49 GCF: ______ B. Find the GCF of the following numbers using prime factorization. 1. 42 and 56 GCF: ______ 4. 64, 48 and 16 GCF: ______ 2. 37 and 51 GCF: ______ 5. 48, 64 and 32 GCF: ______ 3. 49 and 77 GCF: ______ C. Identify the factors and the product in each problem. Note: Numbers 1 and 2 are already done for you. 1. 4(5) = 20 factors: 4,5 product: 20 2. 5(2 x2) = 10x2 factors: 5, 2 x2 product: 10x2 3. 2(7x2y) = 14x2y factors: ______ product: ______ 4. 3a(7a2b3) = 12a3b3 factors: ______ product: ______ 5. -5b3c2(11c2) = -55b3c4 factors: ______ product: ______ 6. 13m3n(3mn) = 39m4n2 factors: ______ product: ______ 7. -17(-3klm2) = 51klm2 factors: ______ product: ______ 2 DISCIPLINE • GOOD TASTE • EXCELLENCE What’s New Marikina City is known for its different festives like the “AngkanAngkan.” Are you familiar with this annual event? This festivity instills -the values of length of connection and solidarity and is celebrated for seven days with the theme of “Ka-angkan Ko, Mabuting Tao.”, More so, festivity showcased more advances with regard to the qualities and great characteristics of Marikeños. https://www.facebook.com/photo.php?fbid=218943521113 9254&set=a.2189431851139590&type=3&theater If you have watched any parade like Angkan-Angkan, Rehiyon-Rehiyon, and others, then answer the following: 1. Can you describe how they were arranged or organized? 2. What are the things that are common to the parade that you have watched? 3. Can you identify things that you observed common in the parade? 4. Why do you think it is useful to find what is common to two or more things? 5. Why is it important to know the commonality of the different things around us? Now, if you are one of the organizers of the said festival or activity, what aspect/s in the parade will you consider for a much better output or result of the program? In this lesson, you will learn how to break down an expression into their commonality and answer the questions: (a)What is greatest common monomial factor? (b)How to find the greatest common monomial factor? What is It A common method of factoring numbers is to completely factor the number into positive prime factors. A prime number is a number whose only positive factors are 1 and itself. In polynomials, the first method for factoring will be factoring out the greatest common factor. This is generally the first thing that we should try as it will often simplify the problem. 3 DISCIPLINE • GOOD TASTE • EXCELLENCE But prior to that, you have to recall these: A monomial is a type of polynomial expression that is the product of constants and nonnegative integer powers of variables, like 2, −4x2 , abc, and −2e2f3g5. While the other types of polynomials are binomial, trinomial, and multinomial. And to factor a polynomial with common monomial expressions, first, we have to factor the numerical coefficient into positive prime factors completely. Simply write the complete factorization of each monomial and find the common factors. Example 1: The GCF of 12, 18, and 36. The GCF is 6. Example 2: The GCF of 10x3 and 4x. 10x3 = 2⋅5⋅x⋅x⋅x 4x = 2⋅2⋅x Therefore, the GCF is 2x What you’ve learned in the examples are all about the greatest common factor (GCF) and how to find this for monomials. Proceed to Factor Polynomials with common monomial factor. How to use this method? To use this method we have to look at all the terms and determine if there is a factor that is in common to all the terms. If you notice that there is a common factor, then factor it out in the polynomial. Example 3: Factor 6ab + 18bc 6ab = 2⋅3⋅a⋅b Express as prime factors 18bc = 2⋅3⋅3⋅b⋅c The common factors are 2⋅3⋅b. Therefore, the GCF is, 6b. 6ab + 18bc = (6b⋅a + 6b⋅3c) = 6𝑏⋅𝑎 6𝑏 + 6𝑏⋅3𝑐 6𝑏 Take out the GCF, then divide the polynomial using the GCFas divisor to get the other factor. = a + 3c The other factor of the given polynomial 6ab + 18bc. = 6b (a + 3c) The factored form of 6ab + 18bc Example 4: Factor 4r2s3 - 8s2t. Step 1: Express each term of the given polynomial as prime factors. 4r2s3 = 22 · r2 · s2 · s 8s2t = 22 ·2 · s2 · t 4 DISCIPLINE • GOOD TASTE • EXCELLENCE Step 2: Determine the GCF. 4r2s3 = 22 · r2 · s2 · s 8s2t = 22 ·2 · s2 · t GCF is 4s2. Step 3: Divide each term of the given polynomial by their GCF. 4𝑟 2 𝑠 3 4𝑠 2 − 8𝑠 2𝑡 = r2s – 2t 4𝑠 2 Factored form of 4r2s3 - 8s2t is 4s2 (r2s – 2t) ANSWER: 4s2 ( r2s – 2t ) Note: The resulting expression is in factored form because it is written as a product of two polynomials, whereas the original expression is a twotermed sum. Here are the steps in factoring polynomials with GCMF: 1. Find the greatest common monomial factor (GCMF). The largest monomial that is a factor of each term of the polynomial 2. Factor it out, then divide the polynomial by the factor found in step 1. The quotient is the other factor. 3. Express the polynomial as the product of two factors (the GCF and the quotient). Remember: The distributive property of multiplication over addition 𝒂 (𝒃 + 𝒄) = 𝒂𝒃 + 𝒂𝒄 In factoring out the greatest common factor we do its reverse. 5 DISCIPLINE • GOOD TASTE • EXCELLENCE What’s More ACTIVITY 1: Find all the prime factors of the given polynomials. Polynomials Factors 1. 30xy 2. 42ab2 3. 56a3b4 4. 49ab5 5. 70a3b3 ACTIVITY 2: Find the greatest common factor of the given polynomials. Polynomials GCF 1. 24y and 30xy 2. 42ab3 and 70a2b2 3. 6x3, 24x2 and 8x 4. 16a2b2, 40a2b3, and 56a3b4 5. 70a3b3, 49ab5 and 42a2b4 ACTIVITY 3: Factor each polynomial completely. Express each polynomial as factors by getting their GCF. 1. 12x + 8y 4. 12x + 15xy + 21x2 2. 70x5y3 – 42x8y2 5. 24a3b2 + 36a2b4 – 60a4b3 3. 18x2 + 45x 6 DISCIPLINE • GOOD TASTE • EXCELLENCE What I Have Learned Fill in the blanks with the appropriate term/s. The _________ is the largest monomial that is a factor of each term of the polynomial. To factor polynomials with GCMF: 1. Find the ________, the largest monomial that is a factor of each term of the polynomial. 2. Factor it out then, _______ the polynomial by the factor found in step 1. The ________ is the other factor. 3. Express the polynomial as the ________ of two factors (the GCMF and the quotient). 7 DISCIPLINE • GOOD TASTE • EXCELLENCE What I Can Do Part of the celebration of the “Angkan-Angkan Festival” is the Salusalo of Kaangkan or clans which is often held at the open grounds space inside the Marikina Sports Center. Each clan occupies an allotted square portion of the venue. Solve the problem using the adjoining UPS Check chart below. UNDERSTAND PLAN What is happening in the problem? What is the question asking you to find? What information is needed to solve the problem? Estimate a reasonable solution. Draw your model. SOLVE The area of a square lot allotted to each clan is numerically equal to its perimeter. Find the length of a side of a square lot. CHECK Show all your thinking to solve the Does my answer make sense? Is my estimate correct? Did I answer the problem. question? Explain your thinking to justify your answer. 8 DISCIPLINE • GOOD TASTE • EXCELLENCE Rubric for the activity below: 1 2 3 Computation The answer and strategies used were incorrect. The answer is incorrect, but the strategy used to solve is correct. The answer and strategies used to solve are correct. Label The answer does not include a label. The answer includes a label but it is not accurate. The answer includes an accurate label. Visual Representation Work does not include a label. Work includes a visual representation but it includes errors. Work includes accurate pictures, number lines and/or equations. Explanation No written explanation is included. Explanation is included but not detailed or in complete sentences. Explanation is detailed and written in complete sentences. Work is not legible. Work is difficult to read but legible. Work is neat and legible. Neatness Assessment Choose the letter that corresponds to the correct answer. 1. Find the greatest common factor of 24, 64, 108. A. 2 B. 4 C. 8 D. 24 2. What is the product of 3𝑥 2 𝑦 and 15𝑥𝑦 2 ? A. 30𝑥 2 𝑦 2 B. 45𝑥 2 𝑦 2 C. 60𝑥 2 𝑦 2 D. 45𝑥 3 𝑦 3 C. a3b3 D. a3b5 3. What is the GCF of a3b3 and a2b5? A. a2b3 B. a2b5 4. The GCF of 14x7 and 10x4 is __________. B. 2x4 A. 2x C. 2x7 D. 10x4 5. What is the GCF of 30w3 + 48w + 12w2? A. 6w B. 6w3 C. 12w D. 12w3 B. 2f 2(1 – 3f) C. 2f 3(8 – 6f 2) D. 3f(1 – 3f) 6. Factor 2f 2 – 6f 3. A. 2f 2(f – 3f 2) 9 DISCIPLINE • GOOD TASTE • EXCELLENCE 7. The factored form of 56a3 – 8a is __________. A. 8a(7a3 – a) C. 8a(7a2 – 1) B. 8a2(35a2 – a) D. 8a2(56a3 – 8a) 8. Find the GCF of the terms: -a9b5 and -ab4 A. a9b5 B. b4 C. ab4 D. a9b4 9. Complete the factors of 7x2y5 + 56x2y4 = 7x2y4 ( _____ ). A. y + 8 B. 7y + 8x C. y + 8x2 D. x2y + 8 10. Factor the polynomial 16x9y9 – 24x6y7 – 16x3y2. A. 8x3(2x6y9 – 3x3y7 – 2y2) C. 8x3y2(2x6y7 – 3x3y5 – 2) B. No common factor except 1 D. 8(2x9y9 – 3x6y7 – 2x3y2) Additional Activities Factor the following polynomials using GCMF: 1) 6v2 – 26v + 20 2) 4ef2 - 4e2f2 + e3f2 3) 12a3 + 9a2 + 15a 4) 13b + 26b2 – 39b3 5) 18x2y4 – 12x2y3 + 24x2y2 10 DISCIPLINE • GOOD TASTE • EXCELLENCE Lesson 2. DIFFERENCE OF TWO SQUARES (DOTS) What’s In At this point, you have already learned how to factor polynomials using their greatest common monomial factor. You can now proceed to the next type of factoring which is the difference of two squares. To check if you have enough knowledge about the next lesson, try to answer the questions indicated below. A. Square the following numbers: 22 = ____ 52 = ____ 92 = ____ 162 = ____ B. Find the principal root of the numbers: √4 = ____ √25 = ____ √81 = ____ √256 = ____ C. Simplify the following: 52 – 22 = _______ (9 + 2) (9 – 2) = _______ 162 – 92 = _______ (16 + 5)(16 – 5) = ______ What’s New Marikina City is known to be the shoe capital of the Philippines. Have you ever visited any shoe shops in this city? Have you observed how the shoes are arranged inside the stores? Why do you think they are arranged that way? In support to the local sapateros of the City of Marikina, the Marikina Cultural, Tourism, Trade and Investment Promotion Office will exhibit the shoe products of the 300 registered shoe and leather manufacturers in the city. The proposed alloted space for the exhibit is the freedom park. Organizers will install a façade inside the parameter of the said park and shall be divided equally for the participants. https://d0ctrine.com/2019/01/09/s hoes-made-in-marikina/ 11 DISCIPLINE • GOOD TASTE • EXCELLENCE 1. How will you arrange the 300 pair of shoes for each façade? Will you arrange it by size? By color? By its type of material? By its style? 2. How many partitions per façade will you create assuming that there are four square facades given that the area of each façade measures 9 m2? 3. How much area will be alotted for each shoe manufacturer? 4. What are the things will you consider in looking for dimensions? 5. What mathematical concepts would you consider in forming different dimensions? Why? 6. Consider that, if the length or the width of one side is increased or decreased by unknown quantities (x), how could you represent the dimensions? What is It The product of the sum and difference of two polynomials is unique in the sense that its middle term vanishes. Since factoring is the reverse of finding the product, the difference of two squares is therefore, the product of the sum and difference of the square roots. That is, x2 – y2 = (x + y)(x– y) How do we factor the difference of two squares of polynomials? Here are the steps in factoring polynomials as DOTS: ● Find the greatest common monomial factor (GCMF), if any. ● Express each term using the pattern, x2 – y2 = (x + y)(x– y) Which is the sum and difference of the square roots of the first and the last terms. ● Check the results. Example 1: Factor x2 – 36y2 (1) The polynomial x2 – 36y2 is obviously the difference of two squares without common factor. (2) Therefore, x2 – 36y2 = x2 – 36y2 = (x)2 - (6y)2 = (x + 6y)(x - 6y). 12 DISCIPLINE • GOOD TASTE • EXCELLENCE To further check the factors, use Distributive Property of Equality. To do this, multiply (x) and (x - 6y), thus we have x2 - 6xy, then multiply (6y) and (x - 6y), we have 6xy - 36y2 and the next step is to get the sum of the products, (x2 – 6xy) + (6xy + 36y2) = x2 – 6xy + 6xy – 36y2 = x2 – 36y2 Notice that we do not have a middle term, this is because when we add –6xy and +6xy the sum is zero (0). Example 2: Factor 4a2x2– 25b2x2 completely. (1) The polynomial 4a2x2– 25b2x2 contains a common factor x2. 4a2 x2– 25b2 x2 = x2 (4a2 – 25b2). Since (4a2 – 25b2) is still factorable using the pattern. (2) Follow the pattern for 4a2 – 25b2 = (2x)2 - (5b)2 (3) Therefore, 4a2 x2– 25b2 x2 = x2(2a + 5b)(2a – 5b). 16 Example 3: Factor 49 − 25𝑥 2 (1) The polynomial is obviously the difference of two squares without common factor. (2) The first term (3) Therefore, 16 49 16 49 4 = ( )2 , the second term 25x2 = (5x)2. 7 4 4 − 25𝑥 2 = (7 + 5x)( 7 – 5x) (4) Check the results using FOIL method. 13 DISCIPLINE • GOOD TASTE • EXCELLENCE What’s More Split Me! Factor the following polynomials completely. 1. a2 – 4 2. 25s2 – t2 3. 9x2 – 16y2 4. 16a2b2c2 – 25c4 5. 4x2a – 25y4 6. m4 – 1 7. 100 – 16b4 8. 36 – (a-b)2 9. [16 – (a + b)2] 10. (m–n)2 - (m + n)2 What I Have Learned How did you factor the difference of two squares? Write the steps: ____________________________ ____________________________ ____________________________ 14 DISCIPLINE • GOOD TASTE • EXCELLENCE What I Can Do Solve the problem using the adjoining UPS Check chart below. UNDERSTAND PLAN What is happening in the problem? What is the question asking you to find? What information is needed to solve the problem? Estimate a reasonable solution. Draw your model. SOLVE The area of the two square facades to be used in the shoe exhibit in Marikina Freedom Park is 20 square meters. Each side of one square façade is twice as long as a side of the other square facade. Find the lengths of the sides of each square wall. CHECK Show all your thinking to solve the Does my answer make sense? Is my estimate correct? Did I answer the problem. question? Explain your thinking to justify your answer. Rubric for the activity below: 1 2 3 Computation The answer and startegies used were incorrect. The answer is incorrect, but the strategy used to solve is correct. The answer and strategies used to solve are correct. Label The answer does not include a label. The answer includes a label but it is not accurate. The answer includes an accurate label. Work does not include a label. Work includes a visual representation but it includes errors. Work includes accurate pictures, number lines and/or equations. No written explanation is included. Explanation is included but not detailed or in complete sentences. Explanation is detailed and written in complte sentences. Work is not legible. Work is difficult to read but legible. Work is neat and legible. Visual Representation Explanation Neatness 15 DISCIPLINE • GOOD TASTE • EXCELLENCE Assessment Choose the letter that corresponds to the correct answer. 1. Multiply (25 – 7) (25 + 7). A. 625 B. 576 C. 484 D. 4 C. 𝑥 2 D. 9 2. Expand: (x + 3) (x – 3). A. 𝑥 2 − 9 B. 𝑥 2 + 9 3. Which of the following polynomials can be factored using the difference of two squares formula? B. 25 – y2 A. x2 + 16 C. x3 + 1 D. x3 – 27 4. Which expression is equivalent to 9x2 – 16? A. (3x + 4)(3x - 4) B. (3x - 4)(3x - 4) C. (3x + 8)(3x - 8) D. (3x - 8)(3x - 8) 5. When factored, the expression 16x2 – 25y2 is equivalent to __________. A. (4x – 5y) (4x + 5y) C. (4x – 5y) (4x - 5y) B. (8x – 5y) (8x + 5y) D. (8x – 5y) (8x - 5y) 6. The factored form of 36 – x6 is ___________. A. (x3 + 6) (x3 - 6) C. (6 – x3) (6 + x3) B. (x6 + 6) (x6 - 6) D. (6 + x6) (6 – x6) 7. Factoring 16x2 – 100 gives ____________. A. (2x – 5) (2x + 5) C. 4(2x – 5) (2x + 5) B. 4(2x – 10) (2x + 10) D. 4(4x – 5) (4x + 5) 8. Which of the following expressions is not a factor of 16x 4 – 81y4? A. 2x – 3y B. 2x + 3y C. 4x – 9y D. 4x2 - 9y2 9. Factor x4 – y4 completely. A. (x2 – y2) (x2 – y2) C. (x – y) (x + y) (x2 + y2) B. (x2 – y2) (x2 + y2) D. (x – y) (x + y) (x2 - y2) 10. Let M = (2x – 7)(2x + 7), and let N = 4x2 – 49. If x = 3, which statement is true about M and N? A. M > N B. M < N C. M = N D. M ≠ N 16 DISCIPLINE • GOOD TASTE • EXCELLENCE Additional Activities Factor the polynomials completely: 1. 𝑥 4 − 1 2. 7𝑥 5 − 7𝑥 3. 2y – 2yz2 4. 4c4 – 4c2 5. – 98 + 2a2 17 DISCIPLINE • GOOD TASTE • EXCELLENCE SUMMATIVE TEST Choose the letter that corresponds to the correct answer. 1. Which is the product of 3𝑥 2 𝑦 and 15𝑥𝑦 2 . A. 30𝑥 2 𝑦 2 B. 45𝑥 2 𝑦 2 C. 60𝑥 2 𝑦 2 D. 45𝑥 3 𝑦 3 B. 2x4 C. 2x7 D. 10x4 B. 2f2 (1 – 3f) C. 2f3 (8 – 6f2) D. 3f (1 – 3f) 2. The GCF of 14x7 and 10x4 is ______. A. 2x 3. Factor 2f2 – 6f3. A. 2f2 (f – 3f2) 4. Find the GCF of -a9b5 and -ab4. A. a9b5 B. b4 C. ab4 D. a9b4 5. Factor the polynomial 16x9y9 – 24x6y7 – 16x3y2. A. 8x3 (2x6y9 – 3x3y7 – 2y2) C. 8x3y2 (2x6y7 – 3x3y5 – 2) B. No common factor except 1 D. 8 (2x9y9 – 3x6y7 – 2x3y2) 6. Expand: (x + 3) (x – 3). A. 𝑥 2 − 9 B. 𝑥 2 + 9 C. 𝑥 2 D. 9 7. Which expression is equivalent to 9x2 – 16? A. (3x + 4) (3x - 4) C. (3x - 4) (3x - 4) B. (3x + 8) (3x - 8) D. (3x - 8) (3x - 8) 8. The factored form of 36 – x6 is __. A. (x3 + 6) (x3 - 6) C. (6 – x3) (6 + x3) B. (x6 + 6) (x6 - 6) D. (6 + x6) (6 – x6) 9. Which of the following expressions is not a factor of 16x 4 – 81y4? A. 2x – 3y B. 2x + 3y C. 4x – 9y D. 4x2 – 9y2 10. Let M = (2x – 7)(2x + 7), and N = 4x2 – 49. If x = 3, which statement is true about M and N? A. M > N B. M < N C. M = N D. M ≠ N 18 DISCIPLINE • GOOD TASTE • EXCELLENCE Development Team of the Module Writer: John Anthony P. Santos – SNNHS Editors: Gemo Parajas (BNNHS) Bielynda Daelo – JDPNHS Analyn C. Santos – MSHS Violentina J. Asuncion – PHS Marites M. Bendoy – THS Amor Agarro – MHS Joel Estudillo – SNNHS Lourdes B. Guyong – NHS Internal Reviewer: Dominador J. Villafria (Education Program Supervisor-Mathematics) Cover Illustrator: Joel J. Estudillo (SNNHS) Management Team: Sheryll T. Gayola Assistant Schools Division Superintendent OIC, Office of the Schools Division Superintendent Elisa O. Cerveza Chief, CID OIC, Office of the Assistant Schools Division Superintendent Dominador J. Villafria Education Program Supervisor-Mathematics Ivy Coney A. Gamatero Education Program Supervisor– LRMS For inquiries or feedback, please write or call: Schools Division Office- Marikina City Email Address: sdo.marikina@deped.gov.ph 191 Shoe Ave., Sta. Elena, Marikina City, 1800, Philippines Telefax: (02) 682-2472 / 682-3989 DISCIPLINE • GOOD TASTE • EXCELLENCE