Can you help with 34,39,40

34. Which of the following statements is correct for the function f (x) = 213 -312 -12x + 5 over the interval [-1, 2]? (a) f(x) has an inflection point and f(r) is increasing over the entire interval [-1, 2]. (b) f(z) has an inflection point and f(r) is decreasing over the entire interval [-1, 2]. (c) f(x) has an inflection point and f(x) has a local maximum in the interval [-1, 2]. (d) f(x) is concave up over the entire interval [-1, 2]. (e) f(x) is concave down over the entire interval [-1, 2]. 35. Find the derivative of y = ecos(3z) - cos(e3z). V36. For what values of a does the graph of f(x) = re- have a horizontal tangent line? V 37. Find the equation of the tangent line to the curve 294 - x y = 23 at the point (1, 1). 38. If f(x) = x", find f'(1). Hint: use logarithmic differentiation. 39. Find the maximum value of the product (x + 1)(y + 2) if x and y are two positive numbers that satisfy x + 2y = 19. 40. If the graph of y = x3 + ax + br - 4 has a point of inflection at (1, -6), what is the value of b? Hint: First find the value of a from the condition that a point of inflection occurs when x =1. Then use the information that (1, -6) is a point on the graph to find b