Use the sign diagram for f'(x) to determine the following. (If an answer does not exist, enter DNE.) f'(x) - 0 + 5 8 (a) the critical values of f(x) (Enter your answers as a comma-separated list.) x=> (b) intervals on which f(x) increases (Enter your answer using interval notation.) (c) intervals on which f(x) decreases (Enter your answer using interval notation.) (d) x-values at which relative maxima occur (Enter your answers as a comma-separated list.) XM (e) x-values at which relative minima occur (Enter your answers as a comma-separated list.) x=