How to fill the plot like this?

Question

Plot[-x^3 + 2 x^2 + 8 x, {x, -5, 5}, Filling -> Axis]

produces this

What's the easiest way to change to something like this

That is, I only need the two "humps".

I have tried this:

Show[
    Plot[-x^3 + 2 x^2 + 8 x, {x, -5, 5}],
    Plot[-x^3 + 2 x^2 + 8 x, {x, -2, 4}, Filling -> Axis]
]

which gives what I want, but it looks too dumb ... and there must be an easier way

Answer 1

Try

Plot[{-x^3 + 2 x^2 + 8 x, ConditionalExpression[-x^3 + 2 x^2 + 8 x, -2 <= x <= 4]}, 
 {x, -5, 5}, 
Filling -> {2 -> Axis}, PlotStyle -> Red]