Unit #7 – Advanced Integration and Applications AP Calculus Day Objective 57 Understand and use the Second Fundamental Theorem of Calculus and functions defined by integrals. Assignment Daily Lessons pages 591 – 595 Day #57 Homework 58 59 Finding integrals by substitution, including changing of variables Daily Lessons pages 599 – 602 and limits of integration. Day #58 Homework Find general and particular solutions for differential equations. Daily Lessons pages 605 – 608 2000 AB #6 Parts a and b 60 Identify and create slope fields that represent the general solutions of differential equations. 2008 AP #5 61 2010 (Form B) AP #5 Quiz #12 Finding the area between two curves. 62 Find volumes of solids of revolution using the disk method. Day #59 Homework 2001 AB #6 Parts a and b 2002 (Form B) AB #5 Parts a and b Daily Lessons pages 611 – 618 Day #60 Homework 2004 AB #6 Parts a, b, and c 2004 (Form B) AB #5 Parts a, b, and c Daily Lessons pages 635 – 638 Finish note packet begun in class. Daily Lessons pages 639 – 641 Day #62 Homework 63 More work with volumes of solids of revolution and find volumes of solids of known cross sections. 64 Quiz #13 2006 AP #3 2011 AB #3 65 Daily Lessons pages 645 – 647 Day #63 Homework Daily Lessons pages 652 – 655 2004 AP #5 2011 AB #4 Finish any of the 4 Free Responses not completed in class Study for Unit #7 Test Unit #7 Test – Advanced Integration and Applications Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 590 The Second Fundamental Theorem of Calculus Functions Defined by Integrals Given the functions, f(t), below, use F ( x) x 1 f (t )dt to find F(x) and F’(x) in terms of x. 1. f(t) = 4t – t2 2. f(t) = cos t Given the functions, f(t), below, use F ( x) x2 1 3. f(t) = t3 f (t )dt to find F(x) and F’(x) in terms of x. 4. f(t) = 6 t Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 591 Second Fundamental Theorem of Calculus Complete the table below for each function. Function F ' ( x) from page 584 Find F ' ( x) by applying the Second Fundamental Theorem of Calculus x F ( x) 4t t 2 dt 1 x F ( x) 4t t 2 dt 1 F ( x) cos t dt x 1 F ( x) cos t dt x 1 x2 3 t dt 1 F ( x) x2 3 t dt 1 F ( x) F ( x) F ( x) x2 1 x2 1 6 t dt 6 t dt Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 592 Find the derivative of each of the following functions. F ( x) 2x 2 2 t 2 dt G ( x) 3 x 2 e cos t dt H ( x) cos x 0 t 2 dt Pictured to the right is the graph of g(t) and the function f(x) is defined to be f ( x) 2x 4 g (t )dt . 1. Find the value of f(0). 2. Find the value of f(2). 3. Find the value of f ' (1) . 4. Find the value of f ' (2) . 5. Find the value of f ' ' (2) . Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 593 Given to the right is the graph of f(t) which consists of three line segments and one semicircle. Additionally, let the function g(x) be defined to be g ( x) x 1 f (t )dt . 1. Find g(–6). 2. Find g(6). 3. Find g ' (6) . 4. Find g ' (2) . 5. Find g ' ' (2) . Give a reason for your answer. 6. Find g ' ' (4) . Give a reason for your Answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 594 The continuous function f is defined on the interval –4 < x < 3. The graph consists of two quarter circles x and one line segment, as show in the figure above. Let g ( x) 1 x 2 f (t )dt . 2 0 Find the value of g(3). Find the value of g(−4). Find the value of g ' (3) . Find the value of g ' ' (2) . Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 595 Name_________________________________________Date____________________Class__________ Day #57 Homework Find the derivative of each of the following functions defined by integrals. 1. g ( x) 3x 2 2. h( x) 4. H ( x) 1 2 t 2t dt 2x 3. f ( x) 5. P( x) x 2 2x 2 x4 (2t 3)dt 3t 2dt 2 3 t dt cos x 5 2t 2 dt e t t dt ln x 6. f ( x) 2 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 596 Pictured to the right is the graph of f(t)and F ( x) 2x 6f (t )dt . Use the graph and F(x) to answer the questions 7 – 11. 7. Find the value of F(0). 8. Find the value of F 1 . 2 9. Find the value of F ' (2) . 10. Find the value of F ' (2.5) . Pictured to the right is the graph of f and G ( x) 11. Find the value of F ' ' (0) x 2f (t)dt . Use the graph to answer questions 12 – 15. 12. Find the value of G(3). 13. Find the value of G(–4). 14. Find the value of G ' (2) . 15. Find the value of G ' ' (5) . Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 597 x If g ( x) t 3e t dt , find each of the following values in questions 16 – 17. 0 16. Find the value of g ' (1). If h( x) 2 x2 17. Find the value of g ' ' (1). 1 t 4 dt , find each of the following values in questions 18 – 19. 18. Find h' ( x). 19. Find h' ' (1). Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 598 Integration of Composite Functions For each of the functions given below, find both f ' ( x) and f ' ( x)dx . f ' ( x) f(x) f ' ( x)dx f ( x) sin 3x f ( x) e cos x f ( x) ln x 2 3 f ( x) x2 3 Anti-differentiation by Pattern Recognition d f ( g ( x)) ____________________________________ dx f ' ( g ( x)) g ' ( x) dx _____________________________ Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 599 Find each of the following indefinite integrals by pattern recognition. 3 cos 3x dx 2 sin(2x 3) dx cos(3x 2)dx 5e 3x dx 2x 3 x 2 5 dx x2x22x dx 2 3x x 2 2 dx 3x 2x 2 3 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 dx Page 600 Ant-differentiation by U–Substitution In each of the eight examples above, the g ' ( x) , or “license to integrate,” existed in the integrand of f ' ( g ( x)) g ' ( x) dx or g ' ( x) was attainable by multiplying by a constant. The g ' ( x) does not always exist and there are times when it is not attainable by multiplication of a constant. Consider the example below. x(2x 1) 3 dx Identify the “inner function,” g(x): _________________________ What is g ' ( x) ? ___________________ Is g ' ( x) part of the integrand? _____________________ Is g ' ( x) attainable by multiplying the integrand by a constant? ________________________ In this case, we must find the anti-derivative by a method known as U-Substitution. Here is how it works. 1. Let u = the inner function, g(x). 4. Rewrite the entire integrand as a polynomial or polynomial type of function in terms of u. Then, anti-differentiate. 2. Find du and solve the equation for dx. 3. Find an expression for x in terms of u. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 601 2xx14 dx 1. Let u = the inner function, g(x). 4. Rewrite the entire integrand as a polynomial or polynomial type of function in terms of u. Then, anti-differentiate. 2. Find du and solve the equation for dx. 3. Find an expression for x in terms of u. 4 Find the value of x 2x 1 dx . Then, check the result using the graphing calculator. 0 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 602 Name_________________________________________Date____________________Class__________ Day #58 Homework In problems 1 – 6, find the indefinite integral. 1. 2. x 3. x 3 sin x 4 dx 4. 1 x dx 5. 5x 1 x 2 dx 6. u 3 x 3 x 4 3 dx 3 1 2 x 2 dx x3 4 2 2 u 3 2du Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 603 For problems 7 and 8, find the indefinite integral by using substitution. 7. x 2 x 1 dx 9. Find the value of 8. 5 1 x 2x 1 x 1 2 x dx dx . Show your work and then check using a graphing calculator. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 604 Solving Differential Equations Examples of Variable Separable Differential Equations Given below are differential equations with given initial condition values. Find the particular solution for each differential equation. 1. dy 6 x 2 6 x 2 and f(–1) = 2 3. dx 2. dy 1 12 x dx 2 x dy x 2 2 x and f(0) = 2 dx 2y 4. 3 2 and f(0) = 2 dy x 2 and f(1) = –3 dx y Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 605 5. dy x 4 ( y 2) and f(0) = 0 dx 6. dy y 1 and f(2) = 0 dx x2 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 606 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 607 The acceleration of a particle moving along the x – axis at time t is given by a(t) = 6t – 2. If the velocity is 25 when t = 3 and the position is 10 when t = 1, then the position x(t) = A. 9t2 + 1 B. 3t2 – 2t + 4 C. t3 – t2 + 4t + 6 D. t3 – t2 + 9t – 20 E. 36t3 – 4t2 – 77t + 55 A particle moves along the x-axis so that, at any time t > 0, its acceleration is given by a(t) = 6t + 6. At time t = 0, the velocity of the particle is –9 and its position is –27. a. Find v(t), the velocity of the particle at any time t. b. Find the net distance traveled by the particle over the interval [0, 2]. c. Find the total distance traveled by the particle over the interval [0, 2]. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 608 Name_________________________________________Date____________________Class__________ Day #59 Homework Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 609 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 610 Slope Fields Graphical Representations of Solutions to Differential Equations A slope field is a pictorial representation of all of the possible solutions to a given differential equation. Remember that a differential equation is the first derivative of a function, f ' ( x) or dy . Thus, the dx solution to a differential equation is the function, f(x) or y. There is an infinite number of solutions to the differential equation dy x 3 . Show your work and dx explain why. For the AP Exam, you are expected to be able to do the following four things with slope fields: 1.________________________________________________________________________________ ________________________________________________________________________________ 2.________________________________________________________________________________ ________________________________________________________________________________ 3.________________________________________________________________________________ ________________________________________________________________________________ 4.________________________________________________________________________________ ________________________________________________________________________________ Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 611 #1 Sketch a slope field for a given differential equation. Given the differential equation below, compute the slope for each point Indicated on the grid to the right. Then, make a small mark that approximates the slope through the point. dy x 1 dx Given the differential equation below, compute the slope for each point Indicated on the grid to the right. Then, make a small mark that approximates the slope through the point. dy x y dx Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 612 #2 Given a slope field, sketch a solution curve through a given point. To the right is pictured the slope field that you developed for the differential equation on the previous page. dy x 1 dx Sketch the solution curve through the point (1, -1). To do this, you find the point and then follow the slopes as you connect the lines. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 613 #3 Match a slope field to a differential equation. Since the slope field represents all of the particular solutions to a differential equation, and the solution represents the ANTIDERIVATIVE of a differential equation, then the slope field should take the shape of the antiderivative of dy/dx. Match the slope fields to the differential equations on the next page. A. B. C. D. E. F. G. H. I. J. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 614 Separate the variables and find the general solution to each differential equation below to determine what the slope field should look like for each. Then, match to the graphs of slope fields on the previous page. 1. dy sin x dx 2. dy 2x 4 dx 3. dy ex dx 4. dy 2 dx 5. dy x 3 3x dx 6. dy 2 cos x dx 7. dy 4 2x dx 8. dy x dx 9. dy x2 dx 10. dy 1 dx x Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 615 #4 Match a slope field to a solution to a differential equation. When given a slope field and a solution to a differential equation, then the slope field should look like the solution, or y. Match the slope fields below to the solutions on the next page. A. B. C. D. E. F. G. H. I. J. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 616 1. y x 2. y x 2 3. y e x 4. y 5. y x 3 6. y sin x 7. y cos x 8. y x 9. y 1 10. y tan x 1 x2 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 617 Shown below is a slope field for which of the following differential equations? Explain your reasoning for each of the choices below. Consider the differential equation dy x to answer the following questions. dx y a. On the axes below, sketch a slope field for the equation. b. Sketch a solution curve that passes through the point (0, –1) on your slope field. c. Find the particular solution y = f(x) to the differential equation with the initial condition f(0) = –1. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 618 Name_________________________________________Date____________________Class__________ Day #60 Homework For the indicated points on each grid, draw the slope field for the given differential equation. 1. dy x y dx 2. dy y dx x 3. dy x 1 dx 4. dy 1 dx x 1 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 619 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 620 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 621 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 622 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 623 AP Calculus Quiz #12 Answer Key & Rubric Multiple Choice: * 1. D C 2. A E 3. C A 4. E A 5. A B 6. A E 7. B A Free Response Part A – 2 points total 4 ____ 1 g (4) f (t )dt 5 2 1 ____ 1 g (2) 2 1 f (t )dt 2 1 f (t )dt 6 Free Response Part B – 2 points total x ____ 1 If g ( x) f (t )dt , then g ' ( x) f ( x) 1 . So, g ' (1) f (1) 4 1 ____ 1 If g ' ( x) f ( x) , then g ' ' ( x) f ' ( x) . g ' ' (1) f ' (1) is undefined because the graph of f has a cusp when x = 1. Free Response Part C – 3 points total ____ 1 Identifies the only relative maximum of g on (–2, 4) to be x = 3. 3 ____ 1 Finds the value of g (3) f (t )dt 1 (1)(1 4) 1 (1)(1) 3 . 1 2 2 ____ 1 On a closed interval, the absolute maximum occurs at an endpoint of the interval or at any relative maximum on the interval. g(–2) = –6, g(3) = 3, and g(4) = 5 . Thus, since g(3) is the 2 greatest, the point (3, 3) is the absolute maximum of g on the interval [–2, 4]. Free Response Part D – 2 points total ____ 1 The graph of g has a point of inflection when g ' ' f ' changes signs. f ' changes signs when the graph of f has a relative maximum or minimum. ____ 1 The graph of f changes from increasing to decreasing at x = 1. Thus, g has a point of inflection at x = 1. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 624 AP CALCULUS QUIZ #12 Name____________________________________________________Date_____________________ Calculator Permitted 1. 2. 3. 4. 5. 6. 7. MULTIPLE CHOICE − Graphing Calculator NOT Permitted The graph of a function, f, which consists of a two line segments and a semi-circle is pictured below. Let G ( x) x 2 2x 2f (t)dt . Use this information to answer questions 1 and 2. 1. What is the value of G(2)? A. 4 + 2π B. –1 + 2π C. 5 + 2π D. 3 + 2π E. 4 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 625 2. Find the value of G ' (2) . A. 4 B. 12 C. 7 D. 27 E. 8 3. If g(x) = x2 3t 3 t 1 1 dt , then what is the value of g ' (2) ? A. –3 B. 8 3 C. 48 65 2 D. 3 E. 12 65 4. If g ( x) A. B. C. D. E. x 0 t 3e t dt , find g ' ' (1) . e 2e e–1 3e 4e Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 626 5. 2x 2 3 x 2 dx 3 B. 1 x 3 2 3 C. 2 x 3 2 3 D. 2x 3 2 E. 3x 3 2 1 A. 4 x 3 2 2 C 2 C 2 C 2 C 1 1 1 1 C 2 x 3 2x 3dx 6. If u = 2x – 3, then C. 1 3 u du 2 E. 1 (2u 3)3 u du 2 4 1 A. 1 u 3 3u 3 du 4 7. If dy dx D. 1 3 u du 4 2 4 B. 1 u 3 3u 3 du 2 2 x and f(0) = –4, find the particular solution to the differential equation. y A. f(x) = 1 x 3 4 3 B. f(x) = 2 x 3 16 3 2 x 3 16 3 C. f(x) = D. f(x) = 1 x 3 3 E. f(x) = 2 x 3 8 3 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 627 FREE RESPONSE The graph of a function f, consisting of three line segments, is pictured above. Let g ( x) x 1 f (t)dt . a. Compute the values of g(4) and g(–2). b. Find g ' (1) and g ' ' (1) . Show or explain your work. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 628 c. Find the coordinates of the absolute maximum of g on the closed interval [–2, 4]. Justify your answer. d. The second derivative of g is not defined at x = 1 and x = 2. Which of these two values is/are coordinates of points of inflection of the graph of g? Justify your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 629 AP CALCULUS *QUIZ #12* Name____________________________________________________Date_______________________ Calculator Permitted 1. 2. 3. 4. 5. 6. 7. MULTIPLE CHOICE − Graphing Calculator NOT Permitted The graph of a function, f, which consists of a two line segments and a semi-circle is pictured below. Let G ( x) x 2 2x 2f (t)dt . Use this information to answer questions 1 and 2. 1. What is the value of G(1)? A. 2 + π B. –1 + 2π C. 1 + 2π D. 3 + 2π E. 1 + π Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 630 2. Find the value of G ' (1) . A. 4 B. 8 C. 7 D. 27 E. 2 3. If g(x) = x2 1 3t 3 t 1 dt , then what is the value of g ' (1) ? A. –3 B. 8 3 C. 24 65 3 D. 2 E. 12 65 4. If g ( x) A. B. C. D. E. x 3 t t e dt , find g ' ' (1) . 0 4e 2e e–1 3e e Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 631 5. 2x 2 x3 2 dx 3 B. 4 x 3 2 3 C. 2 x 3 2 3 D. 2x 3 2 E. 3x 3 2 A. 1 x 3 2 1 1 2 C 2 C 2 C 1 1 1 C 2 C 2 x 6. If u = 2x – 3, then u du u 3u 3 2 x 3dx 2 4 B. 1 u 3 3u 3 du C. 1 3 D. 1 3 2 2 E. 1 4 7. If u du A. 1 (2u 3)3 u du dy dx 4 3 2 4 1 3 du 2 x and f(0) = –4, find the particular solution to the differential equation. y A. f(x) = 2 x 3 16 3 B. f(x) = 1 x 3 4 3 2 x 3 16 3 C. f(x) = D. f(x) = 1 x 3 3 E. f(x) = 2 x 3 8 3 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 632 FREE RESPONSE The graph of a function f, consisting of three line segments, is pictured above. Let g ( x) x 1 f (t)dt . a. Compute the values of g(4) and g(–2). b. Find g ' (1) and g ' ' (1) . Show or explain your work. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 633 c. Find the coordinates of the absolute maximum of g on the closed interval [–2, 4]. Justify your answer. d. The second derivative of g is not defined at x = 1 and x = 2. Which of these two values is/are coordinates of points of inflection of the graph of g? Justify your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 634 Finding the Area between Two Curves An Application of Integration Graph the function f ( x) 12 x 2 2 x 4 and find the value of 0 5 f ( x)dx . Using one color, shade the region for which this value represents the area. Graph the function g ( x) 1 x 4 on the same grid above and then find the value of 2 0 5g ( x)dx . Using a different color, shade the region for which this value represents the area. What do you suppose you would do to find the area of the region that is located in between the graphs of f(x) and g(x)? Find this value. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 635 Now, find the value of the definite integral below if f ( x) 12 x 2 2 x 4 and g ( x) 1 x 4 . Show 2 your work. 0 5 f ( x) g ( x)dx What do you notice about this value? This brings about the general way that we will find the area between two curves. Find the area of the shaded region, R, that is bounded by y = sin(x) and y = x3 – 4x. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 636 3 2 Pictured to the right is the graph of f ( x) x x x 3 cos x 4 3 2 and a line, l, which is tangent to f(x) at the point (0, 3). Find the area of Region R. Find the equation of line l if it is tangent to the graph of f(x) at (0, 3). At what ordered pair, other than (0, 3), does the graph of line l intersect the graph of f(x)? Find the area of Region S. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 637 Pictured to the right are regions R and S, which are formed by the graphs of f ( x) 1 sin(x) and g ( x) 4 x 4 Identify the points of intersection of f(x) and g(x). Find the area of Region R. Find the area of Region S. Find the area of the unshaded region bounded by the graphs of f, g, and the x – axis. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 638 Volumes of Solids of Revolution A solid of revolution is formed when a flat, two-dimensional shape is rotated around an axis. Consider the flat region below to the left. When that region is rotated about the x – axis, the solid pictured below to the right is formed. This objective of this lesson is to learn to find the volume of such a solid. Now, imagine slicing the solid into individual discs of height 1 unit. The volume of one of those discs is V = πr2h, or V = πr2. b Sum of all the discs = a f ( x) Axis of Rotation dx Volume of the Solid = 2 b a f ( x) Axis of Rotation 2 dx Notice that the axis of rotation is the x – axis and the bottom function of the region is also the x – axis. Imagine for a moment what the solid would look like if the axis of rotation were still the x – axis but the bottom function of the region was the line y = c. The solid would look similar except for the fact that there would be a cylinder that is cut out of the center. To find the volume of this solid, we would find the volume of the whole solid that we found previously and then subtract out the solid in the form of a cylinder. In order to do this, we use the formula below to find the volume of such a solid. Volume OuterFunct ion axis 2 InnerFunct ion axis 2 dx b a The “outer function” is defined to be the function that is farther from the axis of rotation. The “inner function” is defined to be the function that is closer to the axis of rotation. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 639 If the axis of rotation is the x-axis or is parallel to the x-axis, the integrand needs to be in terms of x and the limits of integration need to be the x-values of the points of intersection of the curves that form the region being rotated. Consider the region pictured to the right that is bounded by the graphs of y = x2 and y = x + 2. Find the volume of the solid formed when the region is rotated about the x – axis. Find the volume when the region is rotated about the line y = 4. Find the volume when the region is rotated about the line y = –2. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 640 If the axis of rotation is the y-axis or is parallel to the y-axis, the integrand needs to be in terms of y and the limits of integration need to be the y-values of the points of intersection of the curves that form the region being rotated. Consider the region pictured to the right that is bounded by the graphs y = x and y = x – 2. Find the volume when the region is rotated about the y – axis. Find the volume when the region is rotated about the line x = 4. Find the volume when the region is rotated about the line x = 7. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 641 Name_________________________________________Date____________________Class__________ Day #62 Homework Let R be the region bounded by the graphs of y = ln x and the line y = x – 2 as shown below. Though you may use a calculator, show the integral that you found to arrive at your answer. 1. Find the coordinates of the points at which the two graphs intersect each other. Then, find the area of R. 2. Find the volume of the solid generated when R is rotated about the horizontal line y = –3. 3. Write and evaluate an integral expression that can be used to find the volume of the solid generated when R is rotated about the y-axis. Let f and g be the functions given by f ( x) 1 sin(x) and g ( x) 4 x . Let R be the region in the first 4 quadrant enclosed by the y-axis and the graphs of f and g, and let S be the region in the first quadrant enclosed by the graphs of f and g shown to the right. Though you may use a calculator, show the integral that you found to arrive at your answer. 4. Find the points of intersection of f and g. 5. Find the area of the region bounded by the graphs of f and g and the x – axis. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 642 4. Find the volume of the solid generated when R is revolved about the horizontal line y = 8. 5. Find the volume of the solid generated when S is revolved about the horizontal line y = –1. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 643 CALCULATOR NOT PERMITTED Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 644 Volumes of Solids with Known Cross Sections Calculus cannot only be used to find the volume of solids created by revolving two-dimensional shapes around an axis but also the volume of solids formed by cross sections that are geometric shapes. In this lesson, you will derive the formulas for finding volumes of solids given that their cross sections are squares, isosceles right triangles, equilateral triangles, and semi circles. Cross Sections that are Squares Find the area of the square above in terms of f(x) and g(x). If all of the cross sectional areas were added up, the total would be the volume of the solid pictured. How do we write this in calculus using an integral? Cross Sections that are Isosceles Right Triangles Find the area of the triangle above in terms of f(x) and g(x). If all of the cross sectional areas were added up, the total would be the volume of the solid pictured. How do we write this in calculus using an integral? Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 645 Cross Sections that are Equilateral Triangles Find the area of the triangle above in terms of f(x) and g(x). If all of the cross sectional areas were added up, the total would be the volume of the solid pictured. How do we write this in calculus using an integral? Cross Sections that are Semicircles Find the area of the semicircle above in terms of f(x) and g(x). If all of the cross sectional areas were added up, the total would be the volume of the solid pictured. How do we write this in calculus using an integral? What do you notice about the integral-defined formulas for finding the volume of solids with certain cross sections? Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 646 Region R is bounded by y = sin(x) and y = x3 – 4x. Find the volume of the solids formed whose cross sections are the shapes indicated below. The cross sections are perpendicular to the x – axis. a. Cross sections are equilateral triangles b. Cross sections are semi-circles c. Cross sections are isosceles right triangles d. Cross sections are squares. e. Cross sections are rectangles whose height is twice the length of the base. f. Cross sections are rectangles whose height is one-third the length of the base. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 647 Name_________________________________________Date____________________Class__________ Day #63 Homework Let R be the region bounded by the graphs of y = ln x and the line y = x – 2 as shown below. Though you may use a calculator, show the integral that you found to arrive at your answer. 1. Find the volume of the solid whose base is region R that is formed by cross sections that are semi-circles that are perpendicular to the x – axis. 2. Find the volume of the solid whose base is region R that is formed by cross sections that are squares that are perpendicular to the x – axis. Let f and g be the functions given by f ( x) 1 sin(x) and g ( x) 4 x . Let R be the region in the first 4 quadrant enclosed by the y-axis and the graphs of f and g, and let S be the region in the first quadrant enclosed by the graphs of f and g shown to the right. Though you may use a calculator, show the integral that you found to arrive at your answer. 3. Find the volume of the solid whose base is the cross section area of region S and is formed by squares that are perpendicular to the x-axis. 4. Find the volume of the solid whose base is the cross section area of region S and is formed by equilateral triangles that are perpendicular to the x – axis. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 648 Let f and g be the functions given by f ( x) 2 x(1 x) and g ( x) 3( x 1) x for 0 < x < 1. The graphs of f and g are shown in the figure to the right. Though you may use a calculator, show the integral that you found to arrive at your answer. 5. Find the volume of the solid whose base is the cross section of the region bounded by the graphs of f and g and is formed by squares that are perpendicular to the x-axis. 6. Find the volume of the solid whose base is the cross section of the region bounded by the graphs of f and g and is formed by semi-circles that are perpendicular to the x-axis. 7. Find the volume of the solid whose base is the cross section of the region bounded by the graphs of f and g and is formed by equilateral triangles that are perpendicular to the x-axis. 8. Find the volume of the solid whose base is the cross section of the region bounded by the graphs of f and g and is formed by right isosceles triangles that are perpendicular to the x-axis. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 649 CALCULATOR PERMITTED Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 650 CALCULATOR PERMITTED Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 651 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 652 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 653 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 654 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 655 AP Calculus Quiz #13 Answer Key & Rubric Multiple Choice: * 1. C E 2. A C 3. D B 4. D A 5. D B 6. C E 7. E B Free Response Part A – 4 points total ____ 1 Correct integrand and limits for [0, 1] ____ 1 Correct integrand and limits for [1, 3] ____ 1 Correct answer Free Response Part B – 3 points total ____ 1 Correct integrand ____ 1 Correct limits and constant ____ 1 Correct answer Free Response Part B – 3 points total ____ 1 Correct constant and limits ____ 1 Correct integrand 2 1 1 Volume 3 x 2 2 x dx 8 a 2.436 ____ 1 Correct answer Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 656 AP CALCULUS QUIZ #13 Name____________________________________________________Date________________________ Calculator Permitted 1. 2. 3. 4. 5. 6. 7. MULTIPLE CHOICE − Graphing Calculator Permitted 1. Find the area of the region in the first quadrant enclosed by the graphs of y = cos x, y = x and the y – axis. A. 0.127 B. 0.385 C. 0.400 D. 0.600 E. 0.947 2. Find the volume of the solid formed by revolving the region bounded by the graphs of y = 4x – x2 and y = 0 about the x – axis. A. 107.233 B. 34.133 C. 33.510 D. 10.667 E. 129.322 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 657 3. A solid is generated when the region in the first quadrant enclosed by the graph of y = (x2 + 1)3, the line x = 1, the x – axis, and the y – axis is revolved about the x – axis. Its volume is found by evaluating which of the following integrals? 3 2 x 1 dx 1 8 6 B. x 2 1 dx 1 1 2 3 C. x 1 dx 0 1 6 D. x 2 1 dx 0 1 6 E. 2 x 2 1 dx 0 A. 8 4. The region bounded by the graph of y = 2x – x2 and the x – axis is the base of a solid. For this solid, each cross section perpendicular to the x – axis is an equilateral triangle. What is the volume of this solid? A. 1.333 B. 1.067 C. 0.577 D. 0.462 E. 0.267 2 5. The base of a loud speaker is determined by the two curves y = x and 10 y x2 10 for 1 < x < 4 as shown in the figures to the right. For this loud speaker, the cross sections perpendicular to the x – axis are squares. What is the volume of this speaker, in cubic units? A. 2.046 B. 4.092 C. 4.200 D. 8.184 E. 25.711 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 658 6. The slope field pictured below represents all general solutions to which of the following differential equations? A. dy 2x dx B. dy 2 x dx C. dy y dx D. dy y dx E. dy x y dx 7. The graph of a function f, which consists of two line segments and a quarter circle, is pictured to the right. If H ( x) x 2f (t)dt , which of the following statements is true? A. H(4) < H ' (2) < H ' ' (3) B. H(4) < H ' ' (3) < H ' (2) C. H ' (2) < H(4) < H ' ' (3) D. H ' ' (3) < H(4) < H ' (2) E. H ' ' (3) < H ' (2) < H(4) Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 659 FREE RESPONSE Let R and S in the figure to the right be defined as follows: R is the region in the first and second quadrants bounded by the graphs of y = 3 – x2 and y = 2x. S is the shaded region in the first quadrant bounded by the two graphs, the x – axis, and the y – axis. a. Find the area of region S. b. Find the volume of the solid generated when R is rotated about the horizontal line y = –1. c. The region R is the base of a solid. For this solid, each cross section perpendicular to the x – axis is a semi-circle whose diameter lies on the base of the solid. Find the volume of this solid. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 660 AP CALCULUS *QUIZ #13* Name____________________________________________________Date_____________________ Calculator Permitted 1. 2. 3. 4. 5. 6. 7. MULTIPLE CHOICE − Graphing Calculator Permitted 1. Find the area of the region in the first quadrant enclosed by the graphs of y = cos x, y = x and the y – axis. A. 0.127 B. 0.385 C. 0.947 D. 0.600 E. 0.400 2. Find the volume of the solid formed by revolving the region bounded by the graphs of y = 4x – x2 and y = 0 about the x – axis. A. 33.510 B. 34.133 C. 107.233 D. 10.667 E. 129.322 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 661 3. A solid is generated when the region in the first quadrant enclosed by the graph of y = (x2 + 1)3, the line x = 1, the x – axis, and the y – axis is revolved about the x – axis. Its volume is found by evaluating which of the following integrals? 3 2 x 1 dx 1 1 6 B. x 2 1 dx 0 1 2 3 C. x 1 dx 0 8 6 D. x 2 1 dx 1 1 6 E. 2 x 2 1 dx 0 A. 8 4. The region bounded by the graph of y = 2x – x2 and the x – axis is the base of a solid. For this solid, each cross section perpendicular to the x – axis is an equilateral triangle. What is the volume of this solid? A. 0.462 B. 1.067 C. 0.577 D. 1.333 E. 0.267 2 5. The base of a loud speaker is determined by the two curves y = x and 10 y x2 10 for 1 < x < 4 as shown in the figures to the right. For this loud speaker, the cross sections perpendicular to the x – axis are squares. What is the volume of this speaker, in cubic units? A. 2.046 B. 8.184 C. 4.200 D. 4.092 E. 25.711 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 662 6. The slope field pictured below represents all general solutions to which of the following differential equations? A. dy 2x dx B. dy 2 x dx C. dy x y dx D. dy y dx E. dy y dx 7. The graph of a function f, which consists of two line segments and a quarter circle, is pictured to the right. If H ( x) x 2f (t)dt , which of the following statements is true? A. H(4) < H ' (1) < H ' ' (5) B. H ' (1) < H ' ' (5) < H(4) C. H ' ' (5) < H ' (1) < H(4) D. H ' (1) < H(4) < H ' ' (5) E. H(4) < H ' ' (5) < H ' (1) Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 663 FREE RESPONSE Let R and S in the figure to the right be defined as follows: R is the region in the first and second quadrants bounded by the graphs of y = 3 – x2 and y = 2x. S is the shaded region in the first quadrant bounded by the two graphs, the x – axis, and the y – axis. a. Find the area of region S. b. Find the volume of the solid generated when R is rotated about the horizontal line y = –1. c. The region R is the base of a solid. For this solid, each cross section perpendicular to the x – axis is a semi-circle whose diameter lies on the base of the solid. Find the volume of this solid. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 664 AP Calculus Test #8 Answer Key & Rubrics Raw Score to Percentage Conversion Multiple Choice Calculator 1. 2. 3. 4. 5. 6. 7. A D C D B E C Calculator NOT Permitted Free Response Part A – 3 points total ____ 1 g (3) 3 0 f (t )dt 14 (2) 2 1 (1)(1) 1 2 2 ____ 1 g ' (3) = f(3) = –1 ____ 1 g ' ' (3) = undefined because g ' ( x) f ( x) is not differentiable at x = 3. Calculator NOT Permitted Free Response Part B – 3 points total ____ 1 g(x) has a point of inflection when g ' ' ( x) changes signs. ____ 1 g ' ' ( x) changes signs when the graph of g ' ( x) f ( x) has a relative maximum or minimum ____ 1 Thus, g has a point of inflection when x = 0 and x = 3. Calculator NOT Permitted Free Response Part C – 3 points total ____ 1 Correctly finds the values of g(−2) and g(5), as x = −2 and x = 5 are the endpoints of the interval. 2 g (2) f (t )dt f (t )dt 1 (2) 2 4 2 0 5 g (5) 0 f (t )dt 1 (2) 2 1 (1)(1) 1 0 4 2 2 ____ 1 Correctly finds the value of g(4), as x = 4 is the only relative minimum of g on the interval 4 g (4) f (t)dt 0 1 (2) 2 4 1 (2)(1) 1 2 ____ 1 According to the Extreme Value Theorem, the absolute minimum value of g on −2 < x < 5 is –π. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 665 Multiple Choice Non Calculator 8. 9. 10. 11. 12. 13. 14. C D B E C A C Free Response – Non Calculator Part A – 2 points total _____ 1 Correctly drawn zero slopes _____ 1 Correctly drawn non-zero slopes Part B – 6 points total _____ 1 Correct separation of variables _____ 1 Correct anti-differentiation of y _____ 1 Correct anti-differentiation of x _____ 1 Includes constant of integration ln y 1 1 c _____ 1 Uses the initial condition ln 0 1 1 c ln 1 1 c 0 1 c c 1 1 dy y 1 1 x2 dx x 2 y 1 e _____ 1 Correctly solves for y 2 2 2 1x 12 y 1 e 1x 12 y 1 e 1x 12 or y 1 e 1x 12 Part C – 1 point total _____ 1 Since dy dx y 1 x2 represents the slope of the tangent line, then it is only positive for points such that y – 1 > 0, or such that y > 1, provided that x ≠ 0. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 666 AP CALCULUS AB TEST #8 Unit #7 – Advanced Integration and Applications Name______________________________________________________Date_____________________ A GRAPHING CALCULATOR IS REQUIRED FOR SOME PROBLEMS OR PARTS OF PROBLEMS IN THIS PART OF THE EXAMINATION. (1) The exact numerical value of the correct answer does not always appear among the choices given. When this happens, select from among the choices the number that best approximates the exact numerical value. (2) Unless otherwise specified, the domain of a function f is assumed to be the set of all real numbers x for which f(x) is a real number. MULTIPLE CHOICE 1. Let R be the region in the first quadrant bounded by the graphs of y 2 sin x , y e x 3 , and the y – axis as shown in the figure above. Find the volume of the solid generated when R is rotated around the line y = 4. A. 115.380 B. 36.727 D. 23.052 E. 7.338 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 C. 67.036 Page 667 2. The graph of the piecewise linear function f is shown in the figure above. If g ( x) x 2f (t)dt , which of the following values is the greatest? A. g(–3) B. g(–2) C. g(0) D. g(1) E. g(2) 3. The base of a solid is a region in the first quadrant bounded by the x-axis, the y-axis and the graph of the line x + 2y = 8, as shown in the figure below. If the cross sections of the solid perpendicular to the x-axis are semicircles, what is the volume of the solid? A. 12.566 B. 14.661 C. 16.755 D. 67.021 E. 134.041 4. The region bounded by the graph of y = 2x – x2 and the x – axis is the base of a solid. For this solid, each cross section perpendicular to the x – axis is an equilateral triangle. What is the volume of this solid? A. 1.333 B. 1.067 C. 0.577 D. 0.462 E. 0.267 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 668 5. The graph of a function f is shown in the figure below and has a horizontal tangent at x = 4 and x = 8. If g ( x) x 2 2x f (t) dt , what is the value of g ' (3) ? 0 A. –2.5 B. 10 C. –4 D. 13 E. 2 6. Which of the following is the solution to the differential equation condition y( ) 1. A. dy 2 sin x with the initial dx y 2 cos x 3 B. y 2 cos x 1 C. y 2 cos x 3 D. y 2 cos x 1 E. y 2 cos x 1 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 669 7. The graph of the function f shown above has horizontal tangents at x = 2 and x = 5. Let g be the function defined by g ( x) x 0 f (t)dt . For what values of x does the graph of g have a point of inflection? A. 2 only B. 4 only C. 2 and 5 only D. 2, 4, and 5 E. 0, 4, and 6 FREE RESPONSE The graph of a function f, pictured above, consists of a semicircle and two line segments as shown to the x right. Let g be the function given by g ( x) f (t )dt . 0 a. Find the values of g(3), g ' (3) , and g ' ' (3) , if they exist. Show the computations that lead to your answers or give a reason for your answers. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 670 b. Find the x-coordinate of each point of inflection of the graph of g on the open interval –2 < x < 5. Justify your answer. c. On the closed interval –2 < x < 5, what is the absolute minimum value of g. Show your work and justify your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 671 AP CALCULUS AB TEST #8 Test #8: Unit #7 – Advanced Integration and Applications Name______________________________________________________Date_____________________ A GRAPHING CALCULATOR IS NOT ALLOWED FOR THIS SECTION OF THE EXAM. (1) The exact numerical value of the correct answer does not always appear among the choices given. When this happens, select from among the choices the number that best approximates the exact numerical value. (2) Unless otherwise specified, the domain of a function f is assumed to be the set of all real numbers x for which f(x) is a real number. MULTIPLE CHOICE 8. Using the substitution u x , 16 4e 1 x x dx is equal to which of the following? 4 A. 2 e u du B. 2 e u du 2 2 D. 1 e u du 1 C. 2 e u du 1 E. 4 u 1 e 1 2 1 du Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 672 1 9. e 4 x dx = 0 A. e 4 4 B. 4e 4 C. e 4 1 4 D. 1 e 4 4 E. 4 4e 4 10. Region R is the region in the first quadrant bounded by the graphs of f ( x) x , g(x) = 6 – x and the x – axis. Find the area of R. A. 4 B. 22 3 C. 14 3 D. 13 3 E. 6 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 673 11. If f is the function given by f ( x) 2x t 2 t dt , then f ' (2) 4 A. 0 B. 7 2 12 C. 2 D. 12 E. 2 12 12. Shown above is a slope field for which of the following differential equations? A. dy x dx y dy x 3 B. dx y D. dy x 2 dx y 2 E. dy x 3 C. dx y 2 dy x 2 dx y x 13. The graph of a differentiable function f is shown at right. If h( x) f (t )dt , which of the following 0 is true? A. h(6) h' (6) h' ' (6) B. h(6) h' ' (6) h ' (6) C. h ' (6) h(6) h' ' (6) D. h' ' (6) h(6) h ' (6) E. h' ' (6) h ' (6) h(6) Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 674 14. x x 2 A. B. C. 4 dx 1 2 4x 2 4 1 2 x2 4 C C 1 ln x 2 4 C 2 D. 2 ln x 2 4 C E. 2 x2 4 C FREE RESPONSE Consider the differential equation dy y 1 , where x ≠ 0. dx x2 a. On the axes provided, sketch a slope field for the given differential equation at the nine points indicated. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 675 b. Find the particular solution y = f(x) to the differential equation with the initial condition f(2) = 0. c. Describe all points in the x – y coordinate plane for which the slope of the tangent line would be positive. Give a reason for your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 676 Let F(x) = x 3 f (t )dt , where the graph of f(t) is shown to the right. Answer the following questions. 1. Complete the following table for values of F(x). x 2 3 5 6 9 F(x) 2. On what interval(s) is f(t) positive? 3. On what interval(s) is f(t) negative? 4. On what interval(s) is F(x) increasing? Justify your answer. 5. On what interval(s) is F(x) decreasing? Justify your answer. 6. On what interval(s) is F(x) concave up? Justify your answer. 7. On what interval(s) is F(x) concave down? Justify your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 677 Pictured to the right is the graph of f, which consists of two semi-circles and one line segment on the interval [0, 17]. Let g ( x) f (t )dt . x 0 45. Find the values of g(8), g ' (8) and g ' ' (8) . 46. On what interval(s) is the graph of g(x) concave down? Justify your answer. 47. On what interval(s) is the graph of g(x) increasing? Justify your answer. 48. Find all values on the open interval (0, 17) at which g has a relative minimum. Justify your answer. 49. What are the x – coordinates of each point of inflection of g(x)? Justify your answer. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 678 Test #8 Additional Free Response – Calculator NOT Permitted Consider the differential equation dy 2x . dx y a. On the axes provided, sketch a slope field for the given differential equation at the twelve points indicated. b. Write an equation of the tangent line to the graph of f at (1, –1) and use it to approximate f(1.1). Explain why the tangent line gives a good approximation of f(1.1). c. Find the particular solution y = f(x) to the given differential equation with the initial condition f(1) = –1. Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 679 Calculator NOT Permitted Free Response Part A – 2 points total ____ 1 Accurately drawn slope segments are provided for all six points above the x – axis as pictured ____ 1 Accurately drawn slope segments are provided for all six points below the x – axis as pictured. Calculator NOT Permitted Free Response Part B – 3 points total ____ 1 Equation of the tangent line is y = 2x – 3 or equivalent form. ____ 1 f(1.1) –0.8 or 4 5 ____ 1 At x = 1, the value of the function and the value of the tangent line are equivalent because they intersect each other. Thus, at x = 1.1, the tangent line would give a very close approximation of the function because the graph of the tangent line would be a very close under or over approximation depending upon the concavity of the function at x = 1. Calculator NOT Permitted Free Response Part C – 4 points total ____ 1 Separation of variables ____ 1 Correct anti-differentiation of y variable expression: ½y2 ____ 1 Correct anti-differentiation of x variable expression: –x2 + c ____ 1 Correct function y = f(x) = 2 x 2 3 Daily Lessons and Assessments for AP* Calculus AB, A Complete Course Mark Sparks 2012 Page 680
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