Question

PLEASE HELP!!! Select ALL the intervals where f(x)= −x^3 + 3x^2 + 1 is only decreasing:

2 < x < ∞

1 < x < 5

-∞ < x < ∞

0 < x < 2

-∞ < x < 1

-∞ < x < 0

5 < x < ∞

Answer 1

2 < x < ∞ is the only interval on which f(x) is only decreasing.

Explanation:

The graph of f(x) shows that the only interval on which f(x) is increasing is on the interval (0, 2).

The only interval listed which contains no values between 0 and 2 is the interval 2 < x < ∞.