consider the following. (If an answer doesn't exist enter DNE)... please help me with this question ?

f(x ) = 1x4 - 4x2+ 5 (a) Find the interval(s) of increase. (Enter your answer using interval notation.) Find the interval(s) of decrease. (Enter your answer using interval notation.) (b) Find the local minimum value(s). (Enter your answers as a comma-separated list.) Find the local maximum value(s). (Enter your answers as a comma-separated list.) (c) Find the inflection points. smaller x-value (x, y) =( larger x-value (x, y) = Find the interval(s) where the function is concave up. (Enter your answer using interval notation.) Find the interval(s) where the function is concave down. (Enter your answer using interval notation.)