find the intervals where the function is increasing and the intervals where it is decreasing

Question

f(x)= (x^3/3)-(x^2/2)

ok i found its derivative
which is (f1(x)=(x-1)x

my options are increasing a) (0,infinity) b) (-1,0) c(-infinity,0)U(1,infinity)

decreasing a) (0,1) b) (-infinity,0)U(1,infinity)

i cant seem to find the correct answers
because it is increasing from -infinitive to -1. then increasing from -1,0 decreasing from 0,1 and increasing again from (1, infinity)

what im i doing wrong?

Answer 1

You have the correct calculations, but did not organize in a way that helps you get the right answer.

"because it is A(increasing from -infinitive to -1). then B(increasing from -1,0), C(decreasing from 0,1)) and D(increasing again from (1, infinity))"

Statements A, B C and D are all correct.
Since A and B are both increasing, so can you not combine A and B?
Therefore you have two intervals that increase, and one single interval the decreases.

Post again if you still don't find the correct answer.