i only need part c solution i need detailed answer every step

9. A function f defined on (-co,co ) has second derivative f"(x)= ex - 20 . (16 pis) a) Find the intervals of concavity and the x-coordinate(s) of all points of inflection. If there are no points of inflection, say so. b) Given that x = 0 is a critical number of f, does f have a local maximum, a local minimum, or neither, at x = 0? Ye c) Given that x = 2 is a critical number of f, does f have a local maximum, a local minimum, or neither, at x = 2? V him amade