. 2 17. Determine the derivative x for y = 10 tan(2x + 9). b. -3 a. = 20 tan(2x + 9) C. c. There do not exist any x-coordinates for which the function is discontinuous. dx = (20x + 90) tan(2x + 9) d. 3 b. dy = 20 sec (2x + 9) d. day = 10 sec (2x + 9) 12. Let f'(x) = x" - 2x - 3. For what value(s) of x does f(x) have a point of inflection? 18. Determine the x-coordinate of the point for which the tangent is horizontal to the function A(x) - . a. x = -3 c. x = 1 b. x =-1 d. None a. In2 b. 2 d. NI - 13. To the right is the graph of f (x). For what value(s) of x is f(x) decreasing? 19. The position function of an object moving horizontally along a straight line as a function of time is (1) = 815 - 41 , in metres, at time, t, in seconds. Determine the acceleration of the object at t = 4 s. a. x = -1 C. x> 5 a. 248 m/s2 c. 352 m/s2 b. - 1