TAKS Tutorial Calculator Strategies When it comes to the calculator, you are on your own… • Most teachers who will monitor the test know absolutely nothing about these calculators • Even if they did know about the calculator, they are not allowed to assist you in any way Know how to clear the memory of your calculator • If something goes “funky” with the calculator, reset it. • 2nd, Memory (+), Reset (7), All RAM (1), Reset (2) • 2nd, +, 7, 1, 2 2nd 1 2 + 7 Use the “y=“ to match equations with graphs and/or tables. The table below shows various values for x and y. x y −6 23 −2 11 7 −16 11 −28 Enter the answer choices into the calculator through the “y=“ feature and then look at the tables to find a match. Which equation best describes the relationship between x and y? A. y = −3x + 5 B. y = −5x − 7 C. y = −x + 17 D. y = 3x + 41 If your table jumps around as the last one did and you do not wish to scroll • You may set your table to “ASK” you for specific domain (x) values x y −6 23 −2 11 7 −16 11 −28 When “asking” it will not matter where the table starts or what the change in table is… Move the cursor to “Ask” for the Independent variable only If your table jumps around as the last one did and you do not wish to scroll • You may set your table to “ASK” you for specific domain (x) values x y −6 23 −2 11 7 −16 11 −28 Now, when you go to TABLE, you will not see anything except the cursor waiting for you to input an x-value. Then, one at a time, enter the domain values from the given table. The corresponding yvalues come up automatically. To put your calculator table back to the way it was, either reset or… • Go back to TBLSET and put Auto back on for the Indpnt: variable. The next problem could also be done on the calculator. Since there is only one variable in this problem you can use the y = key. Tammy drew a floor plan for her kitchen as shown below. (3x + 5) units (2x + 1) units This problem refers to AREA of the rectangular kitchen. The area formula for a rectangle is A = length times width. Which expression represents the area of Tammy’s kitchen floor in square units? F. 6x2 + 30x + 5 G. 6x2 + 13x + 5 The expression for Area, then, H. 10x + 12 would be (3x + 5)(2x + 1) J. 5x + 6 Tammy drew a floor plan for her kitchen as shown below. (3x + 5) units (2x + 1) units We are going to use “y=“ , since there is only the variable x used in the expressions. Which expression represents the area of Tammy’s kitchen floor in square units? Enter the expression (3x + 5)(2x + 1) 2 F. 6x + 30x + 5 in y1 G. 6x2 + 13x + 5 H. 10x + 12 J. 5x + 6 Tammy drew a floor plan for her kitchen as shown below. (3x + 5) units (2x + 1) units Which expression represents the area of Tammy’s kitchen floor in square units? F. 6x2 + 30x + 5 G. 6x2 + 13x + 5 H. 10x + 12 Changing to this option allows you J. 5x + 6 to follow along as the 2nd function is graphed. F One by one, enter the answer choices into y2. Then, graph. If both equations have exactly the same graph, the two expressions are equivalent and you found your correct answer. is not the correct answer since the two graphs are different. Tammy drew a floor plan for her kitchen as shown below. (3x + 5) units Replace choice F in y2 with choice G and graph. (2x + 1) units Which expression represents the area of Tammy’s kitchen floor in square units? F. 6x2 + 30x + 5 Did you watch as the little 2 G. 6x + 13x + 5 circle made its way around the H. 10x + 12 same parabola? Option G is the J. 5x + 6 correct choice. To be safe, you can check options H & J. If you realize that those two options are linear (no seen exponents for x), their graphs could never be a parabola and thus are not correct answer choices. Use STATPLOT to compare points or scatter plots. , Which point on the grid below best represents the coordinates 8 , 7 ? 3 3 Press the STAT button. A. Point K B. Point M Select EDIT C. Point R D. Point U Enter 8/3 in L1 Which point on the grid below best represents the coordinates 8 , 7 ? 3 3 nd y=) GoWhen to STAT PLOT (2 you enter, the calculator will change the Enter and turn on the plot by fraction into a decimal. entering again. You should see xlist: forinto the L x-coordinate & EnterL17/3 2 ylist: L2 for the y-coordinate. Set the window to the scale in And graph. so you can make a the problem good comparison. , A. B. C. D. Point K Point M Point R Point U And a ycoordinate between 2 & 3. This point has an x-coordinate between 2 and 3. To clear any numbers in a list, you may… • Reset the calculator (2nd + 7 1 2) which will also reset the window on the graph. • 2nd + 4 ClrAllLists • Or while in the list, highlight the list name, press CLEAR, and enter. Do NOT delete! Use the calculator to solve systems. If the system of linear equations 2x + y = 1 and y = − x + 1 are graphed on the same coordinate grid, which of the following is the solution to this system of linear equations? A. (2, 0) B. (0, 2) C. (0.5, 0) D. Not here Graph. Adjust the window, if necessary to see the point of intersection. 2x + y = 1 is not yet calculator friendly! Get the y by itself by subtracting 2x from each side. y = 1 – 2x Enter both equations using the y= feature. You want to go to the CALC feature (2nd TRACE) Select intersect since that is what you are looking for. Since there is only 1 point of intersection, Enter when the calculator says “First curve?”, “Second curve?”, and “Guess” Looking at the answer choices, the correct solution is not there. A. (2, 0) B. (0, 2) C. (0.5, 0) D. Not here The coordinates of the point of intersection, which is the solution, are shown at the bottom of the window. (0, 1) is the point where these two lines intersect. Know how to use the calculator to change decimals to fractions and vice-versa. • Typing in a fraction and pressing ENTER automatically gives you a decimal. • To get a fraction from a decimal, use the MATH button. The highlighted option is convert to Fraction Frac Know how to get back to the home screen. 2nd QUIT will get you there Be sure to use parentheses when fractions are involved. Correct way 2 - 5x y 7 must go into the calculator as y = (2 – 5x)/7 or else you will get the wrong graph! Check it out! The two lines are NOT the same. x6 where x = 4 3x - 1 MUST go into the calculator as (4 + 6)/(3•4-1) or else you will get the wrong answer. Check it out and see what happens when you don’t have the parentheses—both sets! Correct Incorrect Know how to change your table settings. You set the number where you want the table to start You set the scale that you want the values in the table to go by You determine whether you want the table to be filled in automatically as you set it up or to have it wait for you to give it x-values to find. Let’s use this equation. You will see different tables for this same function based upon how you set the table to appear. Starting with -3 and going by 1. Starting with -5 and going by 10. Starting with 2 and going by 0.1. There are different settings you can use on the graphs Makes a thicker line Makes a regular line Makes a regular line and shades above the line Makes a regular line and shades below the line Shows where the graph goes and makes a regular line These options come from backspacing and pressing ENTER Makes a dotted line Shows where the graph goes but makes NO line Practice Problems There are several things you can do with these answer choices to eliminate a few so you won’t have to graph so many. The first thing you should notice is that all of the inequalities have 5 as the y-intercept and a negative slope and no equal sign. Then, whether you plan to use the graphing calculator or not, you need to know that when the inequality sign points to y, as in B and C, the shading is below the line. Since our shading is above the line, we can eliminate these two graphs. For the remaining two choices, you either need to count the slope, starting at the y-intercept or you test the x-intercept of 4 by substituting 4 in for x to see if you get y = 0 or use the calculator to graph and see if the x-intercept is 4. Since today’s tutorial is on calculator usage, that is the method we are going to use. Shaded above To be safe, fraction in ( ). The x-intercept is NOT 4. Wrong choice Shaded above To be safe, fraction in ( ). The x-intercept IS 4. Choice D is verified. This problem can be done a few ways, also. Remember, x-intercepts have y = 0, so you can substitute 0 for y and solve for x. Y-intercepts have x = 0, so you can substitute 0 for x and solve for y. Or you can graph. If you want to do the graphing by hand, remember that there is a blank sheet of graph paper at the end of the math section for you to use as you choose. Since this tutorial is about using the calculator, that is the way we are going to do this problem. The given equation is not calculator friendly. We need to put the equation in y = form. Remember, there is an understood -1 in front of y, due to the subtraction sign. You do NOT have to put the equation in slope-intercept form, just calculator friendly form. The calculator will do the rest. 2x – y = 8 is 2x – 1y = 8. Subtracting 2x, we get -1y = 8 – 2x Then, dividing by -1, we get the calculator friendly form y = (8 – 2x)/-1 You absolutely MUST have the parentheses around the numerator! The x-intercept appears to be 4 The y-intercept is negative. We have no choices with negatives. Let’s eliminate the y-intercept choices. You can either substitute the r-values, by hand or on the calculator home screen, one-by-one to make sure that you get the corresponding n-values. And yes, you must check all of them until you find a value that does not work. Or, you can type the answer choices in y = and match the table of values. Let n = y and r = x, and you will be just fine. Not answer choice B Not answer choice A ALL 4 of the ordered pairs match. This is the one! There is only one variable in these expressions. Put the problem’s expression in y1 and the answer choices, one-byone, in y2. Remember, you want matching graphs. Allows me to watch as the graph is plotted. They matched! Check the others to be sure, though. Definitely not this one, either. Looks like F is the correct answer choice. Doesn’t lookNOPE like NO it, but let’s adjust the window. If this graph is shifted UP, the y-intercept/vertex should be higher. Logically, you should eliminate J because -8 is lower than -3. Let’s type the original function in y1 and the answer choices, one at a time, in y2 and see which parabola shifted UP 5 units. Count the hash marks. The new graph shift up 8 units. Too high! Answer choices will have a thicker line Count the hash marks. The new graph shift up 5 units. This is it! If you count, you can see that between 0 and 1, there are 4 spaces—on each axis. That means that the grid is divided into fourths. T is located on the 3rd space past 0 on the xaxis so its x-coordinate is ¾ . That means we are looking at options G and H. T is located on the 5rd space below 0 on the y-axis so its y-coordinate is -5/4 . That means the correct option is G. Adjustifthe Now, youwindow have noonclue your about calculator these points, to you will match thewant scaletohere. use the YouSTAT are going buttonfrom on yourto -2.5 calculator. 2.5 by ¼ or .25 on each axis. Recall, when you enter fractions into the calculator, they are changed into decimal form. Be sure that the STAT PLOT is turned on with the proper lists. And then graph. This point is way too low to be point T. 5 below zero Try again. 3 to the right of zero This point looks better. Count. 5 below zero 3 to the right of zero We are looking for C when they have given us F. We can solve this equation the “traditional” way—using the “undo” process. 9 104 C 32 5 9 72 C 5 360 9C 40 C Subtract 32 Multiplyby 5 Divide by 9 Alternate method We can solve this equation by using the table feature of the graphing calculator. Enter the equation. Go to the table. Scroll down the table until you find 104 in the y-column Alternate method You need to be Or we could use able to see and in the the graph window where the CALC features of two thelines graphing intersect. calculatorThat place looks way Enter off tothe theequation right. in y1 and 104 in y2. Adjust the window Adjust thetry window again. Let’s the — at You xmax 50.need ymax to be higher than 104 Graph Alternate method Press 2nd TRACE so that you get CALC. Now, select Intersect. Move the cursor to be close to the point of intersection. Enter again for the second curve? And guess? This problem was NOT multiple choice. You have to bubble in your answer correctly! Be careful!!! After going through all that work to get the correct answer, you don’t want the problem to be scored as wrong because you didn’t bubble in the answer properly! 4 0 • 28 An equation can be used to find the total cost of buying square-foot floor tiles to cover an area of floor. Using the table below, find the equation that best represents y, the total cost, as a function of x, the number of square feet to be covered. • • • • • • • F x = 0.35y G y = 0.35x H x = 2.86y J y = 2.86x Verify the correct selection by using the table. Which graph best represents all the pairs of numbers (x, y) such that x + y < -6? Solve for y = y < - x - 6 then use the y = key on the calculator Solve the equation 2a - 6 + 5a 3a + 10 for a. Record your answer and fill in the bubbles on your answer document. Be sure to use the correct place value. Look at the table for the value of x for which y1 = y 2. 25 Which expression is equivalent to (5n - 2)3n - (5n - 2)(n - 1)? A n-1 B 3n 2 - 3n C 10n 2 - 13n + 2 D 10n2 + n - 2 To confirm the solution, check the table to see if you get the same values for the two expressions indicating that they are equivalent or check to see if they generate the same graph. 23 Valerie purchased x tubes of lipstick at $4 each and y bottles of nail polish at $2 each. She spent less than $12, not including tax. Use the grid below to graph the inequality 4x + 2y < 12. Which point represents a reasonable number of lipsticks and bottles of nail polish that Valerie purchased? A (1, 5) B (2, 3) C (1, 3) D (2, 2) Use the home screen to calculate and compare the answers to see which is less than 12. 4 F G H J What is the effect on the graph of the equation y x 2 + 1 when it is changed to y x 2 + 5 ? The slope of the graph changes. The curve translates in the positive x direction. The graph is congruent, and the vertex of the graph moves up the y-axis. The graph narrows. Looking at the graph of the third equation with the tracer ball lets you know that the second equation is the moved up the y-axis. 15 What are the x-intercepts of the graph of the equation y x 2 + x - 12? A x 4, x 3 B x -4, x 3 C x -4, x -3 D x 4, x -3 Looking at the graph, you can see that the x-intercepts are at about –4 and 3. Looking at the tables, you can see that the values of x for which the values of y are 0 are –4 and 3. 47 What is the solution set for the equation 4(3x - 2) 2 = 36? Since the solutions are the values for x for which the value of y = 36, the table shows that the solutions must be between 0 and –1 and between 1 and 2. This eliminates choices A and B. Using the table set in “ASK” and entering the values for x as fractions shows that the value for x for which y=36 is –1/3. C is the correct answer 49 Which shows the functions correctly listed in order from widest to narrowest graph? Using the graph will allow the student to compare. Using the decimal window (zoom 4) will make the comparison easier to analyze visually. 34 The figure below shows the first 3 stages of a fractal. How many circles will the nth stage of this fractal contain? F 2n G 2n H 2n - 1 J 2n - 1 Build a table of values for the information given. Stage # of circles 1 1 2 3 3 7 Enter the three possible equations and, using the “ASK” table set, look for the equation that will give the correct values for number of circles. 6 Which graph best represents a line parallel to the line with the equation y 3x + 4? Using a square standard window, you can see that J is the parallel line. 22 Which of these equations describes a relationship in which every real number x corresponds to a nonnegative real number? F y=x G y=x2 H y=x3 J y = -x Look in the table for the equation that gives nonnegative values for both positive and negative values of x. Using a square window, you can see that only F can be perpendicular to the given line. 42 Oatmeal is packaged in a cylindrical container with the dimensions shown in the drawing. Find the approximate volume of this oatmeal container. F 471 cm 3 G 566 cm 3 H 1413 cm 3 J 5655 cm 3 Remember, all past tutorials can be found on SFHS Math TAKS Resources. • There is a link to that site on the Santa Fe High webpage. • Your teachers will be ready to answer any questions you might have in class. • Come to take the test RESTED! • Look at the posted roll sheets to see what day(s) you are testing and where. We have confidence in YOU! You should have confidence in YOU! Remember, you only need to get a few more than half of the problems correct to pass this test! Do what you know how to do FIRST! AIM For TAKS SUCCESS!!!