Let
\[
f(x)=x^3-\frac32x^2,
\]
which of the following is not correct?
Show Hint
To determine increasing or decreasing intervals,
\[
\boxed{
\begin{aligned}
f'(x)>0 &\Rightarrow \text{Increasing},
f'(x)<0 &\Rightarrow \text{Decreasing}.
\end{aligned}
}
\]
Always analyze the sign of the first derivative on each interval.