4. The graph of the derivative f' (x) of a function is given below. Justify your answers to the following questions. (a) Find all critical numbers (x-coordinates) of f(x) (1 pt) (b) Where is the function y = f(x) increasing? ( 2 pts) (c) Where is the function y = f(x) concave down? ( 2 pts) (d) Find the x-coordinate of the inflection point(s) of y = f(x) (1 pt) - 2 2 5