Answer
The local maximum value is about $3.79$ when $x\approx 0.46$ and the local minimum value is about $2.81$ when $x\approx -0.46$.
Work Step by Step
See the graph of $f(x)=3.3+1.6x-2.5x^3$ below.
We calculate that the local maximum value is about $3.79$ when $x\approx 0.46$ and the local minimum value is about $2.81$ when $x\approx -0.46$.
