Use the graph of the function f(x) displayed below to answer the following questions.
(a) Find the critical values where f'(x) = 0. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
(b) Find the critical values where f'(x) DNE. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
(c) Find the x-coordinate(s) of the relative minima for f(x). (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
(d) Find the x-coordinate(s) of the relative maxima for f(x). (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)