1-5 Parent Functions and Transformations Describe the following characteristics of the graph of each parent function: domain, range, intercepts, symmetry, continuity, end behavior, and intervals on which the graph is increasing/decreasing. 1. f(x) = [[x]] The graph is a horizontal line for all non-integer values of x so the graph is constant for {x | x }. The graph increases by 1 for every integer value of x, so the graph increases for {x | x }. SOLUTION: 2. f(x) = SOLUTION: The graph is continuous for all values of x, so D = {x |x }. The only y-values on the graph are integer values, and all of the integers are included, so R = {y | y }. The graph intersects the y-axis at (0, 0), so there is a y-intercept at (0, 0). The graph intersects the x-axis over [0, 1), so there are x-intercepts for {x | 0 ≤ x < 1, x }. There are no mirror images with respect to the origin, the axes, or any other lines, so the graph has no symmetry. For every integer value of x, the limits if the function are different values from the left and the right, so the graph has a jump discontinuity for {x | x }. The graph approaches negative infinity as x approaches negative infinity so =− The graph approaches infinity as x approaches negative infinity so = . eSolutions Manual - Powered by Cognero . The graph is continuous for all values of x except when x = 0, so D = {x | x ≠ 0, x . The range includes all values of y except when x = 0, so R = {y | y ≠ 0, y }. The graph does not cross the x- or y-axis and thus has no intercepts. The graph has mirror images over the origin, thus he graph is symmetric with respect to the origin. The graph has an infinite discontinuity at x = 0. The graph approaches zero as x approaches negative infinity so = 0. The graph approaches zero as x approaches positive infinity so = 0. The graph is decreasing on (− , 0) and (0, ). Page 1 1-5 Parent Functions and Transformations 3. f(x) = x3 4. f(x) = x4 SOLUTION: SOLUTION: The graph is continuous for all values of x, so D = {x |x }. The range includes all values of y, so R = {y | y }. The range includes all values of y ≥ 0, so R = {y | y ≥ 0, y }. The graph intersects the y-axis at (0, 0), so there is a y-intercept at (0, 0). The graph is mirrored over the origin, so it is symmetric with respect to the origin. The graph approaches infinity as x approaches positive infinity so and = . The graph is increasing on (− eSolutions Manual - Powered by Cognero , ). The graph intersects the y-axis at (0, 0), so there is a y-intercept at (0, 0). The graph is mirror over the y-axis, thus it is symmetric with respect to the y-axis. The graph is continuous. The graph approaches negative infinity as x approaches negative infinity so =− The graph is continuous for all values of x, so D = {x |x }, . The graph is continuous. The graph approaches infinity as x approaches negative infinity so . The graph approaches infinity as x approaches infinity so . The graph is decreasing on (− on (0, ). , 0) and increasing Page 2 1-5 Parent Functions and Transformations 5. f(x) = c 6. f(x) = x SOLUTION: SOLUTION: The graph is continuous for all values of x, so D = {x |x }, The graph is continuous for all values of x, so D = {x |x }. The only y value in the domain is c. Thus, R = {y | y = c, c }. The range includes all values of y, so R = {y | y }. If c = 0, all real numbers are x-intercepts. If c ≠ 0, there are no x-intercepts. The graph intersects the y-axis at (0, 0), so there is a y-intercept at (0, 0). The graph intersects the y-axis at (0, c), so there is a y-intercept at (0, c). The graph is symmetric with respect to the origin. Therefore, it is odd. If c 0, the graph is symmetric with respect to the y-axis. If c = 0, the graph is symmetric with respect to the x-axis, y-axis, and origin. The graph is continuous. The graph approaches negative infinity as x approaches negative infinity so The graph is continuous. The graph approaches infinity as x approaches infinity so . The graph approaches c as x approaches negative infinity so . The graph is increasing for (− , . ). The graph approaches c as x approaches infinity so . The graph is constant on (− eSolutions Manual - Powered by Cognero , ). Page 3 1-5 Parent Functions and Transformations Use the graph of f(x) = function. to graph each –4 SOLUTION: 7. g(x) = g(x) = f(x + 6) − 4. SOLUTION: Therefore, g(x) is the graph of f(x) = 6 units left and 4 units down. g(x) = f(x − 4). Therefore, g(x) is the graph of f(x) = 4 units to the right. 9. g(x) = translated translated 10. g(x) = +3 SOLUTION: 8. g(x) = g(x) = f(x − 7) + 3. Therefore, g(x) is the graph of f(x) = 7 units right and 3 units up. SOLUTION: g(x) = f(x + 3). Therefore, g(x) is the graph of f(x) = 3 units to the left. eSolutions Manual - Powered by Cognero translated translated Page 4 1-5 Parent Functions and Transformations Use the graph of f(x) = to graph each function. 11. g(x) = 13. g(x) = +8 SOLUTION: +4 g(x) = f(x − 6) + 8. SOLUTION: Therefore, g(x) is the graph of f(x) = g(x) = f(x) + 4. units right and 8 units up. Therefore, g(x) is the graph of f(x) = translated 6 translated 4 units up. 14. g(x) = –4 SOLUTION: 12. g(x) = –6 g(x) = f(x + 7) − 4. SOLUTION: Therefore, g(x) is the graph of f(x) = g(x) = f(x) − 6. units left and 4 units down. Therefore, g(x) is the graph of f(x) = translated 7 translated 6 units down. eSolutions Manual - Powered by Cognero Page 5 1-5 Parent Functions and Transformations Describe how the graphs of f(x) = [[x]] and g(x) are related. Then write an equation for g(x). 16. 15. SOLUTION: There are several important characteristics for f(x) = [[x]]. First determine if the graph increasing from left to right. Identify if the graph has open dots on the left or right. Determine the length of each horizontal line. Also identify how far a horizontal segment on the x-axis or y-axis is from the origin. The graph of g(x) is increasing from left to right which is the same as f(x) = [[x]]. The graph of g(x) has closed dots on the left and open on the right which is the same as f(x) = [[x]]. Each horizontal line is 1 unit which is the same as f(x) = [[x]]. The horizontal bar on the y-axis is shifted five units down or the horizontal bar on the x-axis is shifted five units to the right. Thus the graph of g(x) is the SOLUTION: There are several important characteristics for f(x) = [[x]]. First determine if the graph increasing from left to right. Identify if the graph has open dots on the left or right. Determine the length of each horizontal line. Also identify how far a horizontal segment on the x-axis is from the origin. The graph of g(x) is increasing from left to right which is the same as f(x) = [[x]]. The graph of g(x) has closed dots on the left and open on the right which is the same as f(x) = [[x]]. Each horizontal line is 1 unit which is the same as f(x) = [[x]]. The horizontal bar on the x-axis is shifted three units to the left. Thus, the graph of g(x) is the graph of f(x) translated 3 units to the left when g(x) = [[x + 3]], or translated 3 units up when g(x) = [[x]] + 3. graph of f(x) translated 5 units to the right when g(x) = [[x – 5]], or translated 5 units down when g(x) = [[x]] − 5. eSolutions Manual - Powered by Cognero Page 6 1-5 Parent Functions and Transformations 18. 17. SOLUTION: There are several important characteristics for f(x) = [[x]]. First determine if the graph increasing from left to right. Identify if the graph has open dots on the left or right. Determine the length of each horizontal line. Also identify how far a horizontal segment on the x-axis or y-axis is from the origin. SOLUTION: There are several important characteristics for f(x) = [[x]]. First determine if the graph increasing from left to right. Identify if the graph has open dots on the left or right. Determine the length of each horizontal line. Also identify how far a horizontal segment on the x-axis or y-axis is from the origin. The graph of g(x) is decreasing from left to right which is the opposite or a reflection of f(x) = [[x]]. The graph of g(x) is decreasing from left to right which is the opposite so the graph g(x) is reflected from f(x) = [[x]]. The graph of g(x) has closed dots on the left and open on the right which is the opposite as f(x) = [[x]]. Each horizontal line is 1 unit which is the same as f(x) = [[x]]. The horizontal bar on the x-axis is shifted five units to the right. Thus the graph of g(x) is the graph of f(x) reflected in the y-axis and translated 5 units right when g(x) = [[5 – x]], or reflected in the yaxis and translated 5 units up when g(x) = [[−x]] + 5. eSolutions Manual - Powered by Cognero The graph of g(x) has open dots on the left and closed on the right which is the opposite of f(x) = [[x]]. Each horizontal line is 1 unit which is the same as f(x) = [[x]]. The horizontal bar on the x-axis is shifted two units to the left. The graph of g(x) is the graph of f(x) reflected in the y-axis and translated 2 units to the left when g(x) = [[−x – 2]], or reflected in the yaxis and translated 2 units down when g(x) = [[−x]] − 2. Page 7 1-5 Parent Functions and Transformations 19. PROFIT An automobile company experienced an Describe how the graphs of f(x) = |x| and g(x) are related. Then write an equation for g(x). unexpected two-month delay on manufacturing of a new car. The projected profit of the car sales before the delay p(x) is shown below. Describe how the graph of p(x) and the graph of a projection including the delay d(x) are related. Then write an equation for d(x). 20. SOLUTION: SOLUTION: Since there is a two-month delay, the graph of g(x) is the graph of p(x) translated 2 units (months) to the right. The equation for d(x) can be written by replacing x with x − 2 in p(x). So, d(x) = 10(x – 2)3 – 70(x – 2)2 + 150(x – 2) – 2. The central characteristic of f(x) = x is the point where the two lines meet. For our purposes here, it can be considered as a vertex or a critical point. This point is at (0, 0) for the parent function. Identifying where it shifts will help you identify g(x). Note that these are translations only. For reflections and dilations, we will have to consider more aspects of the graph. The vertex is at (8, 0), so the vertex is translated 8 unit to the right. Therefore, the graph of f(x) is also translated 8 unit to the right. Now we need to identify an equation for g(x). The x-coordinate tells us what changed inside the absolute value symbols. Treat this like a zero for a linear equation. If the coordinate is 8, the expression inside the absolute value should be x − 8. Thus, the graph of g(x) is the graph of f(x) translated 8 units to the right; g(x) = | x – 8 |. eSolutions Manual - Powered by Cognero Page 8 1-5 Parent Functions and Transformations 21. 22. SOLUTION: SOLUTION: The central characteristic of f(x) = x is the point where the two lines meet. For our purposes here, it can be considered as a vertex or a critical point. This point is at (0, 0) for the parent function. Identifying where it shifts will help you identify g(x). Note that these are translations only. For reflections and dilations, we will have to consider more aspects of the graph. The central characteristic of f(x) = x is the point where the two lines meet. For our purposes here, it can be considered as a vertex or a critical point. This point is at (0, 0) for the parent function. Identifying where it shifts will help you identify g(x). Note that these are translations only. For reflections and dilations, we will have to consider more aspects of the graph. The vertex is at (0, −5), so the vertex is translated 5 units down. Therefore, the graph of f(x) is also translated 5 units down. The vertex is at (−4, −8), so the vertex is translated 4 unit to the left and 8 units down. Therefore, the graph of f(x) is also translated 4 unit to the left and 8 units down. Now we need to identify an equation for g(x). Now we need to identify an equation for g(x). The y-coordinate tells us what was added outside of the absolute value symbols. It describes the vertical shift from the origin. The y-coordinate is −5, so we need to subtract 5. Thus, the graph of g(x) is the graph of f(x) translated 5 units down; g(x) = | x | − 5. The x-coordinate tells us what changed inside the absolute value symbols. Treat this like a zero for a linear equation. If the coordinate is −4, the expression inside the absolute value should be x + 4. The y-coordinate tells us what was added outside of the absolute value symbols. It describes the vertical shift from the origin. The y-coordinate is −8, so we need to subtract 8. Thus, the graph of g(x) is the graph of f(x) translated 4 units to the left and 8 units down; g(x) = | x + 4 | − 8. eSolutions Manual - Powered by Cognero Page 9 1-5 Parent Functions and Transformations Identify the parent function f(x) of g(x), and describe how the graphs of g(x) and f(x) are related. Then graph f(x) and g(x) on the same axes. 24. g(x) = 3| x | – 4 SOLUTION: 23. SOLUTION: The central characteristic of f(x) = x is the point where the two lines meet. For our purposes here, it can be considered as a vertex or a critical point. This point is at (0, 0) for the parent function. Identifying where it shifts will help you identify g(x). Note that these are translations only. For reflections and dilations, we will have to consider more aspects of the graph. g(x) = 3f(x) − 4, so the graph of g(x) is the graph of f(x) = |x| expanded vertically and translated 4 units down. The expansion is represented by the coefficient of 3 on the outside of f(x). The translation down is represented by the subtraction of 4 on the outside of f(x). The vertex is at (1, −2), so the vertex is translated 1 unit to the right and 2 units down. Therefore, the graph of f(x) is also translated 1 unit to the right and 2 units down. Now we need to identify an equation for g(x). 25. g(x) = 3 SOLUTION: The x-coordinate tells us what changed inside the absolute value symbols. Treat this like a zero for a linear equation. If the coordinate is 1, the expression inside the absolute value should be x − 1. The y-coordinate tells us what was added outside of the absolute value symbols. It describes the vertical shift from the origin. The y-coordinate is −2, so we need to subtract 2. g(x) = 3f(x + 8), the graph of g(x) is the graph of f(x) translated 8 units to the left and expanded vertically. The translation left is represented by the addition of 8 on the inside of f(x). The expansion is represented by the coefficient of 3 on the outside of f(x). g(x) = | x − 1 | − 2 eSolutions Manual - Powered by Cognero Page 10 1-5 Parent Functions and Transformations 26. g(x) = 28. g(x) = −5[[x – 2]] SOLUTION: SOLUTION: g(x) = 4f(x + 1), so the graph of g(x) is the graph of f(x) translated 1 unit to the left and expanded vertically. The translation left is represented by the addition of 1 on the inside of f(x). The expansion is represented by the coefficient of 4 on the outside of f(x). g(x) = −5f(x − 2), so the graph of g(x) is the graph of f(x) translated 2 units to the right, expanded vertically, and reflected in the x-axis. The translation right is represented by the subtraction of 2 on the inside of f(x). The expansion is represented by the coefficient of 5 on the outside of f(x).The reflection is represented by the negative coefficient on the outside of f(x). 27. g(x) = 2[[x – 6]] SOLUTION: g(x) = 2f(x − 6), so the graph of g(x) is the graph of f(x) translated 6 units to the right and expanded vertically. The translation left is represented by the subtraction of 6 on the inside of f(x). The expansion is represented by the coefficient of 2 on the outside of f(x). eSolutions Manual - Powered by Cognero 29. g(x) = −2| x + 5| SOLUTION: g(x) = −2f(x + 5), so g(x) is the graph of f(x) translated 5 units to the left, expanded vertically, and reflected in the x-axis. The translation left is represented by the addition of 5 on the inside of f(x). The expansion is represented by the coefficient of 2 on the outside of f(x). The reflection is represented by the negative coefficient on the outside of f(x). Page 11 1-5 Parent Functions and Transformations 30. g(x) = Graph each function. +7 32. SOLUTION: g(x) = f(x) + 7, so g(x) is the graph of f(x) compressed vertically and translated 7 units up. The SOLUTION: compression is represented by the coefficient of on the outside of f(x). The translation up is represented by the addition of 7 on the outside of f(x). On the interval [−∞, −2), graph y = −x2. On the interval [−2, 7), graph y = 3. On the interval [7, ∞), graph y = (x − 5)2. Multiple points must be found for x = −2 and x = 7 because of the domain intervals. 31. g(x) = SOLUTION: g(x) = f(x + 3), so g(x) is the graph of f(x) translated 3 units to the left and compressed vertically. The translation left is represented by the addition of 3 on the inside of f(x). The compression is represented by the coefficient of Since f(−2) = 3 and f(7) = 6, draw dots at (−2, 3) and (7, 6). f(−2) ≠ −4 and f(7) ≠ 3, so the points (−2, −4) and (7, 3) are not included in the graph. Draw circles at these points. on the outside of f(x). eSolutions Manual - Powered by Cognero Page 12 1-5 Parent Functions and Transformations 33. 34. SOLUTION: SOLUTION: On the interval [−∞, −6), graph y = −x + 4. On the interval [−6, 4), graph y = . On the interval [4, ∞), graph y = 6. On the interval [−∞, −5), graph y = 74. On the interval [−2, 2], graph y = x3. On the interval (3, ∞), graph y = . Multiple points must be found for x = −6 and x = 4 because of the domain intervals. Since f(−2) = −8 and f(2) = 8, draw dots at (−2, −8) and (2, 8). Since f(−6) = f(−5) ≠ 4 and f(3) ≠ and f(4) = 6, draw dots at and (4, 6). , so the points (−5, 4) and (3, ) are not included in the graph. Draw circles at these points. f(−6) ≠ −2 and f(4) ≠ , so the points (−6, −2) and are not included in the graph. Draw circles at these points. eSolutions Manual - Powered by Cognero Page 13 1-5 Parent Functions and Transformations 36. 35. SOLUTION: SOLUTION: On the interval (−∞, −4), graph y = 2. On the interval (−∞, −3), graph y = |x − 5|. On the interval [−1, 3), graph y = 4x − 3. On the interval [4, ∞), graph y = . Since f(−1) = −7 and f(4) = 2, draw dots at (−1, −7) and (4, 2). f(−3) ≠ −8 and f(3) ≠ 9, so the points (−3, −8) and (3, 9) are not included in the graph. Draw circles at these points. eSolutions Manual - Powered by Cognero On the interval [−1, 1), graph y = x4 − 3x2 + 5. On the interval [3, ∞), graph y = . Since f(−1) = 9 and f(3) = 4, draw dots at (−2, 3) and (7, 6). f(−4) ≠ −2 and f(1) ≠ 3, so the points (−4, −2) and (1, 3) are not included in the graph. Draw circles at these points. Page 14 1-5 Parent Functions and Transformations left end of each segment. Plot each of the following segments. 37. SOLUTION: On the interval (−∞, −1), graph y = −3x − 1. On the interval (−1, 3], graph y = 0.5x + 5. On the interval (3, ∞), graph y = −|x − 5| + 3. x-coordinates dot circle 0 3 3 7 7 11 11 13 13 14 14 18 18 19 19 20 20 y-coordinates 0.25 0.29 0.32 0.33 0.34 0.37 0.39 0.41 0.42 Multiple points must be found for x = −1 and x = 3 because of the domain intervals. Since f(−1) = −2 and f(3) = 6.5, draw dots at (−1, −2) and (3, 6.5). f(−1) ≠ 4.5 and f(3) ≠ 1, so the points (−1, 4.5) and (3, 1) are not included in the graph. Draw circles at these points. 38. POSTAGE The cost of a first-class postage stamp in the U.S. from 1988 to 2008 is shown in the table below. Use the data to graph a step function. SOLUTION: Let x = 0 represent 1988. The price changes at the beginning of the year, so the dots will appear on the eSolutions Manual - Powered by Cognero 39. BUSINESS A no-contract cell phone company charges a flat rate for daily access and $0.10 for each minute. The cost of the plan can be modeled by c(x) = 0.1[[x]] + 1.99, where x is the number of minutes used. a. Describe the transformation(s) of the parent function f(x) = [[x]] used to graph c(x). b. The company offers another plan in which the daily access rate is $2.49, and the per-minute rate is $0.05. What function d(x) can be used to describe the second plan? c. Graph both functions on the same graphing calculator screen. d. Would the cost of the plans ever equal each other? If so, at how many minutes? SOLUTION: Page 15 1-5 Parent Functions and Transformations a. c(x) = a × f(x) + b. The value of a is less than 1, so the graph of f(x) compressed vertically. The value of b is 1.99, so the graph of f(x) is translated 1.99 units up. horizontal distance in feet such that x = 0 corresponds to the initial point. b. The per-minute rate is the value of a and the access rate is b in c(x) = a × f(x) + b. Therefore, d(x) = 0.05[[x]] + 2.49. c. a. Describe the transformation(s) of the parent d. Yes; the plans will equal each other at 10 minutes. Use the Intersect function of the calculator to find the intersection of the graphs. Notice that the intersection is the segment from x = 10 to x = 11. function f(x) = x2 used to graph g(x). b. If a second golfer hits a similar shot 30 feet farther down the fairway from the first player, what function h(x) can be used to describe the second golfer’s shot? c. Graph both golfers’ shots on the same graphing calculator screen. d. At what horizontal and vertical distances do the paths of the two shots cross each other? SOLUTION: a. Rewrite the function in the form f(x) = a(x − h)2 + k. 0.176x – 0.0004x2 = –0.0004x2 + 0.176x = –0.0004(x2 – 440x) [0, 20] scl: 2 by [0, 5] scl: 0.5 Creating a table of values will also confirm when c(x) = d(x). = –0.0004(x2 – 440x + 48,400) – (–0.0004)(48,400) g(x) = −0.0004(x − 220)2 + 19.36 So, the graph of g(x) is the graph of f(x) translated 220 units to the right, compressed vertically, reflected in the x-axis, and translated 19.36 units up. b. This is a shift right, so h(x) = g(x − 30) or h(x) = −0.0004(x − 250)2 + 19.36. c. 40. GOLF The path of a drive can be modeled by the function shown, where g(x) is the vertical distance in feet of the ball from the ground and x is the eSolutions Manual - Powered by Cognero Page 16 1-5 Parent Functions and Transformations Use the graph of f(x) to graph g(x) = |f(x)| and h(x) = f(|x|). 41. f(x) = SOLUTION: |f(x)| replaces all of the negative y-values with the d. Use the Intersectionfeature of your calculator. corresponding positive y-values. If f(–3) = , then |f(–3)| = . To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. f(|x|) replaces all of the negative x-values with the The shots will cross paths at a horizontal distance of 235 feet and a vertical distance of 19.27 feet. corresponding positive x-values. If f(–3) = , then f(|–3|) = . To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. eSolutions Manual - Powered by Cognero Page 17 1-5 Parent Functions and Transformations 42. f(x) = SOLUTION: |f(x)| replaces all of the negative y-values with the corresponding positive y-values.If f(–6) = undefined , then f(|–6|) = undefined. |f(x)| replaces all of the negative y-values with the corresponding positive y-values. If f(–3) = , then |f(–3)| = . To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. f(|x|) replaces all of the negative x-values with the corresponding positive x-values. If f(–6) = undefined , then f(|–6|) = . To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. f(|x|) replaces all of the negative x-values with the corresponding positive x-values. If f(–2) = , then f(|–3|) =. To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. 43. f(x) = x4 – x3 – 4x2 SOLUTION: eSolutions Manual - Powered by Cognero Page 18 1-5 Parent Functions and Transformations 44. f(x) = x3 + 2x2 – 8x – 2 SOLUTION: |f(x)| replaces all of the negative y-values with the corresponding positive y-values. If f(–7) = , then . |f(–3)| = To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. f(|x|) replaces all of the negative x-values with the corresponding positive x-values. If f(–3) = , then f(|–3|) = . To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. eSolutions Manual - Powered by Cognero Page 19 1-5 Parent Functions and Transformations 45. f(x) = +5 46. f(x) = –6 SOLUTION: SOLUTION: |f(x)| replaces all of the negative y-values with the corresponding positive y-values. If f(–4) = , then |f(–4)| = . |f(x)| replaces all of the negative y-values with the corresponding positive y-values. If f(–1) = , then |f(–1)| = . To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. To graph g(x) = |f(x)|, reflect the range with respect to the x-axis for all elements of the domain where f(x) is less than zero. f(|x|) replaces all of the negative x-values with the corresponding positive x-values. If f(–4) = , then f(|–4|) = . f(|x|) replaces all of the negative x-values with the corresponding positive x-values. If f(–1) = , then f(|–1|) = To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. eSolutions Manual - Powered by Cognero . To graph h(x) = f(|x|), replace the range for x < 0 with a reflection of the range for x > 0 with respect to the y-axis. Page 20 1-5 Parent Functions and Transformations 47. TRANSPORTATION In New York City, the standard cost for taxi fare is shown. One unit is equal to a distance of 0.2 mile or a time of 60 seconds, when the car is not in motion. a. Write a greatest integer function f(x) that would represent the cost for x units of cab fare, where x > 0. Round to the nearest unit. b. Graph the function. c. How would the graph of f(x) change if the fare for the first unit increased to $3.70 while the cost per unit remained at $0.40? Graph the new function. SOLUTION: a. When there is only a fraction of a unit, we must round up. For example, if 3.4 units are used, the customer will be charged for 4 units. To accomplish this, use [[x + 1]] when x is not a whole number. b. c. If the fare for one unit increased to $3.70, and the cost per unit was still $0.40, then the cost per trip must have increased to $3.30. This will cause a vertical translation of the graph of $0.80. The graph of f(x) is translated 0.8 unit up. eSolutions Manual - Powered by Cognero Page 21 1-5 Parent Functions and Transformations 48. PHYSICS The potential energy in joules of a spring that has been stretched or compressed is given by p(x) = , where c is the spring constant and x is the distance from equilibrium. When x is negative, the spring is compressed, and when x is positive, the spring is stretched. Write and graph the function with the given parent function and characteristics. 49. f(x) = ; expanded vertically by a factor of 2, translated 7 units to the left and 5 units up SOLUTION: g(x) = +5 a. Describe the transformation(s) of the parent function f(x) = x2 used to graph p(x) = 4.5x2. b. The graph of the potential energy for a second spring passes through the point (3, 315). Find the spring constant for the spring and write the function for the potential energy. The shift 5 units up is represented by an addition of 5 after f(x), or f(x) + 5. The shift 7 units left is represented by the addition of 7 inside f(x), or f(x + 7). The vertical expansion by a factor of 2 is represented by the coefficient 2 outside f(x), or 2f(x). Therefore, g(x) = 2f(x + 7) + 5. SOLUTION: a. p(x) = cf(x), so the parent function is multiplied by a constant and the transformation is a vertical expansion. b. Use (3, 315) to solve for c in p(x). 50. f(x) = [[x]]; expanded vertically by a factor of 3; reflected in the x-axis; translated 4 units down SOLUTION: g(x) = −3[[x]] – 4 p(x) = 35x2 eSolutions Manual - Powered by Cognero The reflection in the x-axis is represented by negative coefficient in front of f(x), or −f(x). The vertical expansion by a factor of 3 is represented by the coefficient of 3 in front of f(x), of 3f(x). The shift 4 units down is represented by the subtraction of 4 after f(x), or f(x) − 4. Therefore, g(x) = −3f(x) − 4. Page 22 1-5 Parent Functions and Transformations PHYSICS The distance an object travels as a function of time is given by f(t) = at2 + v0t + 53. a = 4, v0 = 8, x0 = 1 SOLUTION: x 0, where a is the acceleration, v0 is the initial velocity, and x 0 is the initial position of the object. Describe the transformation(s) of the parent function f(t) = t2 used to graph f(t) for each of the following. 51. a = 2, v0 = 2, x0 = 0 SOLUTION: Substitute the values then complete the square to identify the transformations. translated 2 units to the left; expanded vertically; translated 7 units down 54. a = 3, v0 = 5, x0 = 3 SOLUTION: translated one unit left; translated one unit down 52. a = 2, v0 = 0, x0 = 10 SOLUTION: Substitute the values to identify the transformations. translated units left; expanded vertically; translated units down translated 10 units up eSolutions Manual - Powered by Cognero Page 23 1-5 Parent Functions and Transformations Write an equation for each g(x). 55. 56. SOLUTION: SOLUTION: The parent function is f(x) = . The graph of g(x) appears to be f(x) shifted 4 units up and 3 units to the right. Therefore, we have . Use (4, 6) to determine if there is a dilation. The parent function is f(x) = x3. Reference the critical point of the parent graph at (0, 0). The graph of g(x) appears to have this point at (5, –8). The graph also appears to be reflected. So, the graph of g(x) appears to be f(x) shifted 5 units to the left, shifted 8 units down, and then reflected in the y-axis. The reflection causes the shift left to appear to be a shift right in the graph. Therefore, we have g(x) = − (x − 5)3 − 8. Use (3, −4) to determine if there is a dilation. There is a dilation of 2, so g(x) = + 4. The dilation is 0.5, so g(x) = −0.5(x – 5)3 – 8. eSolutions Manual - Powered by Cognero Page 24 1-5 Parent Functions and Transformations 57. 58. SOLUTION: SOLUTION: The parent function is f(x) = . Use the initial point of the parent graph at (0, 0) to estimate the translation.The graph of g(x) appears to be f(x) shifted 4 units left and 6 units down. The parent function is f(x) = [[x]]. With a greatest integer function, more than one transformation can lead to the same graph of g(x). One possibility is a dilation with no shift at all. Let a represent the dilation and use (4, 1), a point on g(x), to determine a. There is also an obvious dilation. Let a represent the dilation and use (0, 2) to solve for a. There is no reflection, so a = 4 and g(x) = 4 – 6. eSolutions Manual - Powered by Cognero Therefore, one possible function is g(x) = [[x]]. Page 25 1-5 Parent Functions and Transformations 59. SHOPPING The management of a new shopping Identify the parent function f(x) of g(x), and describe the transformation of f(x) used to graph g(x). mall originally predicted that attendance in thousands would follow f(x) = for the first 60 days of operation, where x is the number of days after opening and x = 1 corresponds with opening day. Write g(x) in terms of f(x) for each situation below. a. Attendance was consistently 12% higher than expected. b. The opening was delayed 30 days due to construction. c. Attendance was consistently 450 less than expected. 60. SOLUTION: SOLUTION: The graph is a quadratic, so the parent function is a. A consistent percentage change is represented by a dilation, or a coefficient in front of f(x). Therefore, g(x) = 1.12f(x). f(x) = x2. The graph is reflected in the x-axis because it resembles an upside-down version of the parent graph. b. There is no affect on f(x). While the opening is delayed, the number of days after the opening, which determines the domain of the function, is unaffected. Use like points to gauge the translation. In the parent graph, the minimum is located at x = 0. The maximum of the graph is the minimum of the parent graph translated down 3 units and left 4 units. c. To represent a consistently less value, subtract the difference from f(x). Therefore, g(x) = f(x) − 0.45. So far, we have g(x) = −a(x + 4)2 − 3 where a represents the unknown compression or expansion. Use the given point to identify the value of a. Substituting 0.5 for a, g(x) = −0.5(x + 4)2 − 3, which means that the parent graph was compressed vertically. Therefore, the graph of g(x) is the graph of f(x) translated 4 units to the left, compressed vertically, reflected in the x-axis, and translated 3 units down. eSolutions Manual - Powered by Cognero Page 26 1-5 Parent Functions and Transformations 62. 61. SOLUTION: The parent function is f(x) = x3. The graph is reflected in the x-axis because it resembles an upside-down version of the parent graph. Use like points to gauge the translation. In the parent graph, the point of inflection, or the point where the graph appears to curve in at the middle is located at x = 0. The point of inflection of g(x) is 2 units up and 4 units to the right. So far, we have g(x) = −a(x − 4)3 + 2 where a represents the unknown compression or expansion. Use the given point to identify the value of a. SOLUTION: The parent function is f(x) = . Use like points to gauge the translation. In the parent graph, the vertical asymptote is located at x = 0. This is unchanged in g(x), so there is no horizontal translation. In the parent function, the horizontal asymptote is located at y = 0 and in g(x) it is located at y = −6, so there is a translation down of 6 units. The graph is also expanded vertically by an unknown factor. So far, we have g(x) = − 6 where a represents the unknown expansion. Use the given point to identify the value of a. Substituting 3 for a, g(x) = −3(x − 4)3 + 2, which means that the parent graph was expanded vertically. Therefore, the graph of g(x) is the graph of f(x) translated 4 units to the right, expanded vertically, reflected in the x-axis, and translated 2 units up.. Substituting 4 for a, g(x) = − 6 , which means that the parent graph was expanded vertically. Therefore, the graph of g(x) is the graph of f(x) expanded vertically and translated 6 units down. eSolutions Manual - Powered by Cognero Page 27 1-5 Parent Functions and Transformations Use f(x) to graph g(x). 63. SOLUTION: The parent function is f(x) = . The graph is reflected in the x-axis because it resembles an upside-down version of the parent graph. Use like points to gauge the translation. In the parent graph, the point where the graph begins is located at x = 0. In g(x), this point located 3 units to the right and 5 units up. 64. g(x) = 0.25f(x) + 4 SOLUTION: f(x) is dilated by a factor of 0.25 and then translated up 4. Do this to each piece of the graph. Remember that in the graph of f(x), (x, y) = (x, f(x)). Therefore, in the graph of g(x), (x, y) = (x, g(x)) or (x, 0.25f(x) + 4). 1st line So far, we have g(x) = −a + 5 where a represents the unknown compression or expansion. Use the given point to identify the value of a. 2nd line Ray (x, f(x)) (−6, 6) to (−2, −4) (−2, 1) to (6, −1) (6, 4) (x, g(x)) (−6, 5.5) to (−2, 3) (−2, 4.25) to (6, 3.75) (6, 5) Therefore, the graph of g(x) is the graph of f(x) translated 3 units to the right, reflected in the x-axis, and translated 5 units up. eSolutions Manual - Powered by Cognero Page 28 1-5 Parent Functions and Transformations 65. g(x) = 3f(x) – 6 66. g(x) = f(x – 5) + 3 SOLUTION: SOLUTION: f(x) is dilated by a factor of 3 and then translated down 6. Do this to each piece of the graph. Remember that in the graph of f(x), (x, y) = (x, f(x)). Therefore, in the graph of g(x), (x, y) = (x, g(x)) or (x, 3f(x) − 6). f(x) is 5 shifted units right and 3 units up. Do this to each piece of the graph. In this graph, the x- and ycoordinates are both shifted. For each segment, add 5 to the x-coordinate and add 3 to the y-coordinate. 1st line 2nd line Ray (x, f(x)) (−6, 6) to (−2, −4) (−2, 1) to (6, −1) (6, 4) (x, g(x)) (−6, 12) to (−2, −18) (−2, −3) to (6, −9) (6, 6) eSolutions Manual - Powered by Cognero 1st line 2nd line Ray (x, f(x)) (−6, 6) to (−2, −4) (−2, 1) to (6, −1) (6, 4) (x, g(x)) (−1, 9) to (3, −1) (3, 4) to (11, 2) (11, 7) Page 29 1-5 Parent Functions and Transformations 67. g(x) = −2f(x) + 1 Use f(x) = SOLUTION: 68. g(x) = 2f(x) + 5 f(x) is dilated by a factor of −2 and then translated up 1. Do this to each piece of the graph. Remember that in the graph of f(x), (x, y) = (x, f(x)). Therefore, in the graph of g(x), (x, y) = (x, g(x)) or (x, −2f(x) + 1). 1st 2nd Ray (x, f(x)) (−6, 6) to (−2, −4) (−2, 1) to (6, −1) (6, 4) – 4 to graph each function. SOLUTION: (x, g(x)) (−6, −11) to (−2, 9) (−2, −1) to (6, 3) (6, −7) eSolutions Manual - Powered by Cognero Page 30 1-5 Parent Functions and Transformations 69. g(x) = −3f(x) + 6 71. g(x) = f(2x + 1) + 8 SOLUTION: SOLUTION: 70. g(x) = f(4x) – 5 SOLUTION: eSolutions Manual - Powered by Cognero Page 31 1-5 Parent Functions and Transformations 72. MULTIPLE REPRESENTATIONS In this problem, you will investigate operations with functions. Consider f(x) = x2 + 2x + 7, g(x) = 4x + 3, and h(x) = x2 + 6x + 10. a. TABULAR Copy and complete the table below for three values for a. 73. ERROR ANALYSIS Danielle and Miranda are describing the transformation g(x) = [[x + 4]]. Danielle says that the graph is shifted 4 units to the left, while Miranda says that the graph is shifted 4 units up. Is either of them correct? Explain. SOLUTION: Sample answer: Both; the greatest integer function is the step function in which a shift of a units left also shifts the graph a units up. b. VERBAL How are f(x), g(x), and h(x) related? c. ALGEBRAIC Prove the relationship from part b algebraically. SOLUTION: a. So, a shift of a units left is identical to a shift of a units up. b. The values for h(a) and f(a) + g(a) are equal for each value of a, so h(x) may be the sum of f(x) and g(x). c. We think h(x) = f(x) + g(x), so we need to set these equal to each other and simplify until we get congruent expressions on each side of the equal sign. eSolutions Manual - Powered by Cognero Page 32 1-5 Parent Functions and Transformations 74. REASONING Let f(x) be an odd function. If g(x) is 75. Writing in Math Explain why order is important a reflection of f(x) in the x-axis and h(x) is a reflection of g(x) in the y-axis, what is the relationship between f(x) and h(x)? Explain. when transforming a function with reflections and translations. SOLUTION: Sample answer: Order is important because different graphs can be obtained depending on the order the transformations are performed. For example, if (a, b) is on the original graph and there is a translation 6 units up and then a reflection in the x-axis, the resulting point will be (a, −b – 6). f(x) and g(x) represent the same function; If f(x) = x3, an odd function, then g(x) = −x3, a reflection of f(x) in the x-axis. Likewise, h(x) = −(−x3) or x3, a reflection of g(x) in the y-axis. Therefore, f(x) = h(x). SOLUTION: f(x) = x3 However, if (a, b) is reflected in the x-axis first and then translated 6 units up, the resulting point will be (a, −b + 6). g(x) = −f(x) = −x3 h(x) = g(−x) = −f(−x) = −(−x)3 = x3 eSolutions Manual - Powered by Cognero Page 33 1-5 Parent Functions and Transformations REASONING Determine whether the following statements are sometimes, always, or never true. Explain your reasoning. 76. If f(x) is an even function, then f(x) = |f(x)|. SOLUTION: x2. All of the Consider the basic even function, f(x) = values of f(x) are positive, so |f(x)| = f(x) for all values of x. 77. If f(x) is an odd function, then f(−x) = −|f(x)|. SOLUTION: Consider the odd function f(x) = x3. f(–x) = (–x)3 = –x3 –|f(x)| = –|x3| Notice from the graphs of these functions that they are not equal. Now consider an even function in which negative values are a part of the output. Translate the graph down 4 units and we get g(x) = x2 − 4. This function is still even because g(x) = g(−x). However, there are some values where g(x) is negative. |g(x)| will only have positive values, so g(x) ≠ |g(x)|. However, f(x) = 0 is also an odd function and f(–x) = –| f(x)| for all x, so the statement is sometimes true. 78. If f(x) is an even function, then f(−x) = −|f(x)|. SOLUTION: Consider the basic even function, f(x) = x2. All of the values are positive, so all of the values of f(–x) will also be positive. This is becaue the square eliminates the negatives f(–x) = (–x)2 = x2 –|f(x)| = –|x2| = –x2 eSolutions Manual - Powered by Cognero Page 34 1-5 Parent Functions and Transformations 79. CHALLENGE Describe the transformation of f(x) = if (−2, −6) lies on the curve. SOLUTION: Sample answer: There are many different curves that can include (–2, –6). One example would be to simply translate the endpoint of the parent function. It is normally at (0, 0), so the translation will be 2 units left and 6 units down. From the graph, –|f(x)| ≠ f(–x). g(x) = f(x + 2) – 6 = Now consider an even function in which some output values are negative, like f(x) = –x2. f(–x) = –(–x)2 = –x2 –|f(x)| = –|–x2| = –x2 From the graph, –|f(x)| = f(–x). Thus, sometimes when f(x) is an even function, then f(−x) = −|f(x). f(x) = –x2 is an even function and f(–x) = –| f(x)| for all x. However, f(x) = x2 is an even function and f(–x) ≠ –| f(x)|. eSolutions Manual - Powered by Cognero Page 35 1-5 Parent Functions and Transformations 80. REASONING Suppose (a, b) is a point on the graph of f(x). Describe the difference between the transformations of (a, b) when the graph of f(x) is expanded vertically by a factor of 4 and when the graph of f(x) is compressed horizontally by a factor of 4. SOLUTION: Sample answer: A vertical expansion of f(x) by a factor of 4 would move (a, b) to (a, 4b). A horizontal compression by a factor of 4 would move (a, b) to Find the average rate of change of each function on the given interval. 82. g(x) = −2x2 + x – 3; [−1, 3] SOLUTION: g(x) = −2x2 + x – 3; [−1, 3] g(3) = −2(3)2 + (3) – 3 g(3) = −18 + 3 − 3 = −18 g(−1) = −2(−1)2 + (−1) – 3 g(−1) = −2 − 1 − 3 = −6 . For example, if f(x) = x2, then a vertical expansion by a factor of 4 would be g(x) = 4x2. A horizontal compression by a factor of 4 would be h(x) = (4x)2. Let (a, b) = (2, 4). Then in the vertical expansion, (2, 4) would move to (2, 16). In the horizontal compression, (2, 4) moves to . 83. g(x) = x2 – 6x + 1; [4, 8] SOLUTION: g(x) = x2 – 6x + 1; [4, 8] g(8) = (8)2 – 6(8) + 1 g(8) = 64 – 48 + 1 g(8) = 17 g(4) = (4)2 – 6(4) + 1 g(4) = 16 – 24 + 1 g(4) = –7 81. Writing in Math Use words, graphs, tables, and equations to relate parent functions and transformations. Show this relationship through a specific example. SOLUTION: See students’ work. eSolutions Manual - Powered by Cognero Page 36 1-5 Parent Functions and Transformations 84. f(x) = −2x3 – x2 + x – 4; [−2, 3] SOLUTION: f(x) = −2x3 – x2 + x – 4; [−2, 3] f(3) = −2(3)3 – (3)2 + (3) – 4 f(3) = –54 – 9 + 3 – 4 f(3) = –64 Use the graph of each function to describe its end behavior. Support the conjecture numerically. 85. q(x) = – SOLUTION: f(−2) = −2(−2)3 – (−2)2 + (−2) – 4 f(–2) = 16 – 4 – 2 – 4 f(–2) = 6 x –100 –10 –5 5 10 100 q(x) 0.12 1.2 2.4 –2.4 –1.2 –0.12 As x → ∞, the denominator of the fraction will increase and the value of the fraction will approach 0, so q(x) will approach 0. eSolutions Manual - Powered by Cognero Page 37 1-5 Parent Functions and Transformations 86. f(x) = 87. p(x) = SOLUTION: x –25 –10 –5 5 10 25 SOLUTION: f(x) 0.0008 0.005 0.02 0.02 0.005 0.0008 As x → ∞, the denominator of the fraction will increase and the value of the fraction will approach 0, so f(x) will approach 0. x –1000 –100 –10 –5 5 10 100 1000 p(x) 0.99501 0.95146 0.82143 0.375 0.5 1.71429 1.05155 1.00502 As x → ∞, the fraction will get closer and closer to , so p(x) will approach 1. eSolutions Manual - Powered by Cognero Page 38 1-5 Parent Functions and Transformations Use the graph of each function to estimate its yintercept and zero(s). Then find these values algebraically. 89. SOLUTION: 88. SOLUTION: From the graph, it appears that f(x) will intersect the y-axis at (0, 0). Find f(0). From the graph, it appears that f(x) will intersect the y-axis at about (0, 12). Find f(0). Because f(0) = 0, there is a y-intercept at (0, 0). Because f(0) = 13, there is a y-intercept at (0, 13). From the graph, it appears that there is an x-intercept near x = −1, x = 0, and x = 2. Let f(x) = 0 and solve for x. From the graph, it appears that there is an x-intercept near x = 2 and x = 6. Let f(x) = 0 and solve for x. Therefore, the zeros of f are 0, 2, and −1. Therefore, the zeros of f are about 5.73 and 2.27. eSolutions Manual - Powered by Cognero Page 39 1-5 Parent Functions and Transformations 92. LOTTERIES In a multi-state lottery, the player must guess which five of the white balls numbered from 1 to 49 will be drawn. The order in which the balls are drawn does not matter. The player must also guess which one of the red balls numbered from 1 to 42 will be drawn. How many ways can the player complete a lottery ticket? 90. SOLUTION: SOLUTION: From the graph, it appears that there is no y-intercept for the graph of f(x). Find f(0). For the 5 white balls: Order does not matter, so the number of possibilities can be represented by a combination. There are 49 possible choices and we are choosing 5, so we use 49C5. Because f(0) = is undefined, there is no y-intercept. For the red ball, there are 42 options. Therefore, the total number of possibilities is 49C5 · 42 = 80,089,128. From the graph, it appears that there is an x-intercept near x = 3. Let f(x) = 0 and solve for x. no y-intercept; zero: 3; 93. SAT/ACT The figure shows the graph of y = g(x), which has a minimum located at (1,−2). What is the maximum value of the function h(x) = −3g(x) − 1? Therefore, the zero of f is 3. 91. GOVERNMENT The number of times each of the first 42 presidents vetoed bills are listed below. What is the standard deviation of the data? 2, 0, 0, 7, 1, 0, 12, 1, 0, 10, 3, 0, 0, 9, 7, 6, 29, 93, 13, 0, 12, 414, 44, 170, 42, 82, 39, 44, 6, 50, 37, 635, 250, 181, 21, 30, 43, 66, 31, 78, 44, 25 SOLUTION: Enter the data in your calculator and find the standard deviation of the population of data. A6 B5 C3 D2 E It can not be determined from the information given SOLUTION: The minimum of g(x) is –2. h(x) is a transformation of g(x). In order to obtain the critical point of h(x) that corresponds with the minimum of g(x), multiply this value by –3 and then subtract 1. –2(–3) – 1 = 5 The standard deviation is about 118.60. eSolutions Manual - Powered by Cognero Page 40 1-5 Parent Functions and Transformations 96. REVIEW What is the effect on the graph of y = k x2 94. REVIEW What is the simplified form of as k decreases from 3 to 2? ? A The graph of y = 2x2 is a reflection of the graph of y = 3x2 in the y-axis. B The graph is rotated 90° about the origin. C The graph becomes narrower. D The graph becomes wider. SOLUTION: SOLUTION: As k decreases from 3 to 2, the graph of y = k x2 becomes wider. 95. What is the range of y = F {y | y ≠ ±2 G {y | y ≥ 4} H {y | y ≥ 0} J {y | y ≤ 0} ? } The correct choice is D. SOLUTION: The smallest possible value for x2 is 0. Therefore, the smallest possible value of is = 4. As x approaches positive or negative infinity, x2 approaches positive infinity. Therefore, the value of also approaches infinity. The correct choice is G. eSolutions Manual - Powered by Cognero Page 41