Consider the equation below. (If an answer does not exist, enter DNE.) f(x) = x4 − 50x2 + 7

(a) Find the interval on which f is increasing. (Enter your answer using interval notation.)

- Find the interval on which f is decreasing. (Enter your answer using interval notation.)

(b) Find the local minimum and maximum values of f.

- local minimum value

- local maximum value

(c) Find the inflection points.
(x, y) = (smaller x-value)
(x, y) = (larger x-value)

- Find the interval on which f is concave up. (Enter your answer using interval notation.)

- Find the interval on which f is concave down.(Enter your answer using interval notation.)