Determine the open intervals on which the function is increa

Determine the open intervals on which the function is increasing, decreasing, or f(x) = -1/5 x^3 increasing decreasing constant

Solution

f(x) =- x^3/5

So f\'(x) = -(3/5)x^2

Is always negative in (-infinity ,0) and (0 , infinity)

So function is decreasing in this interval.

And f\'(x) = 0 at x=o

So f(x) is constant at x=0