Soluzione del esercizio 201 di Matematica.verde, Vol. 1 (seconda edizione)

You can think of the shape as two rectangles next to one another.

The one on the left has area: $(2x+1)(x+1)=2x^2+x+2x+1=2x^2+3x+1$, and the one on the right has area: $[3x+2-(x+1)](x-1)=(2x+1)(x-1)=2x^2+x-2x-1=2x^2-x-1$.

So the area of the shape is $(2x^2+3x+1)+(2x^2-x-1)=4x^2+2x$.