Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision Multiple-choice questions π 3 1 If y = |cos (x)|, the rate of change of y with respect to x at x = k, < k < , is: 2 2 A sin (k) B sin (k) C cos (k) D cos (k) E k sin (1) 2 The equation of the tangent to the curve with equation y = ex, at the point (–1, e), is given by: x A y = e + 1 x 1 B y= + +e e e C y = 1 ex 1 2 D y= x+ e e E y = ex 3 The minimum value of e –x + 2ex occurs where x = A 0 B 2 2 1 C –2 loge 2 D 1 E 2.82 1 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision x 4 For f: R R, f(x) = ex e , the coordinates of the turning point of the graph of y = f(x) are: A (1, 0) B (1, e ) 2 C (1, e ) 1 D (1, e ) E (1, 0) 5 The equation of the normal of the graph with equation y = e 0.25x at the point (0, 1) is: A y = 4x 1 B y = 4x + 1 C y= x 4 D y = 4 x + 1 E y=4x+1 6 Using the approximation f(x + h) f(x) + h f (x) where f(x) = ex, with x = 0, the approximate value of e0.025 is found to be: A 0.025 B 0.975 C 1.025 D 1.0253 E 1.025315 2 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision 7 The line with equation y = 3x + 5 and the curve with equation y = 2e–x + 3 intersect at the point (0, 5). At this point, the acute angle between the line and the curve is where tan is equal to: 1 A 2 B 1 C 2 D 3 E 5 8 If f(x) = loge 4x, then f (3) is equal to: 1 A 3 1 B 12 C loge 12 D 1.079 E 4 loge 4 9 The equation of the tangent to y = loge 3x at the point where x = 1 is: A y = x 1 + loge 3 B y = x + loge 3 3 C y= x 1 D y= x 1 E y = 3x 10 The equation of the tangent to f(x) = 3e2x + 1 at the point where x = 0.5 is: A y = 6e2x B y = 6ex + 1 C y = 6xe 3e D y = x6e 3e + 1 E y = 6ex 3e + 1 3 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision 11 If f(x) = 2e(3x² + 1) then: A f (1) = 2e4 B f (1) = 2e4 + 6 C f (1) = 6e4 D f (1) = 6e4 + 6 E f (1) = 12e4 12 Let y = 2xex where x R. The minimum value of y is: A 2 2 B (e ) 2 C e D 2 E 2e 13 If z = loge (x) then z is approximately equal to: A loge (x + x) B loge (x) C 1 x x D x 1 E x 14 For y = sin x + cos x the maximum value of y is: A 1 B 2 C 2 D 2 2 E 3 4 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision 15 The equation of the tangent to the curve with equation y = ex 1 at the point where the curve crosses the y-axis is: A y=x B y = x 1 C y=2x 1 D y = 2 x E y = 2x Short-answer questions (technology-free) 1 Find the derivative of each of the following with respect to x: a 2 sin (x2) b x3 sin x c sin x ex d log e x 3x e 5e3x cos (2x) 2 Find the the gradient of the normal to the curve with equation y = 2 cos 2x at the point where x = 6 3 Find the equation of the tangent to the curve of y = 2e–x – 2 at the origin. 4 The volume V (litres) of water in a tank at time t (hours) is given by V(t) = 3 sin ( 12t ) + 1 2 a Find the volume of water in the tank at time t = 24 b Find the rate of change of volume of the water in the tank when t = 24 5 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision 5 If f(x) = 2x loge ( 3x2 ) : a find f (x) b find f (1) c find f (e) 6 The cross-section of a fault in a floor can y be modelled by the function f: [0, 3] R where f(x) = 3 – 3 cos ( 2x3 ) and where y = f(x) x cm is measured from a point O on the floor in a straight line and f(x) cm is the height of the fault at the point x. 0 3 x a How far from O does the fault reach a height of: i 3 cm? ii 1.5 cm? iii 4.5 cm? b What is the gradient of y = f(x) at each of these points? Extended-response questions The volume of water, w megalitres, at time t months in a dam is modelled by the formula t t w(t) = 4 0.5 sin ( 3 ) cos ( 6 ), t ≥ 0 where t is measured from the first of January. 1 Find the volume of water in the dam on 1 January. 2 State the period of w. 6 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision dw 3 a Find the exact rate of change of volume, dt , when t = 2 b Find the values of t for which the rate of change of volume is zero, t [0,12]. 4 The graph of y = w(t) is shown. y t dw On the same set of axes sketch the graph of y = dt . 7 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision Answers to Chapter 11 Test A Answers to multiple-choice questions 1 B 2 E 3 C 4 C 5 B 6 C 7 B 8 A 9 A 10 B 11 E 12 B 13 D 14 B 15 B Answers to short-answer (technology-free) questions 1 a 4x cos (x2) b x3 cos (x) + 3x2 sin (x) c (cos (x) – sin (x))e–x 1 – loge (x) 3x2 d e (15 cos (2x) – 10 sin (2x))e3x 2 1 2 3 3 y = –2x 1 4 a 2 π b 4 2 5 a 2 loge(3x ) – 2 2 b 2 loge(3 ) – 2 8 Essential Mathematical Methods 3 & 4 CAS Chapter 11 Differentiation of transcendental functions: SAC 4 Revision 2 c 2 loge(3 ) – 4 6 a i 0.75 cm and 2.25 cm ii 0.5 cm and 2.5 cm iii 1 cm and 2 cm b i ii 2π and –2π 3 π and – 3 π iii π 3 and – π 3 Answers to extended-response questions 1 3 megalitres 2 12 months 3 a ( 3 +1)π 12 b t = 1, 5 and 9 months 4 y y = w(t) 1 5 9 t y= dw dt 9