Submit Answer 9. [-/0.71 Points] DETAILS TAMUBUSCALC1 3.1.009. 0/6 Submissions Used Let f(x) = 9vx - 3x. (a) Find the interval(s) where f(x) is increasing. (Enter your akswer using interval notation.) (b) Find the interval(s) where f(x) is decreasing. (Enter your answer using interval notation.) (c) Find the x-value(s) of all local maxima of f(x). (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.) X = (d) Find the x-value(s) of all local minima of f(x). (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.) X = Submit