Answer
$x^2+2x$
Work Step by Step
The given figure can be decomposed in two rectangles: a small rectangle with dimensions
$x-(x-1)=1$
and
$(x+3)-x=3$
and a big rectangle with dimensions
$x+3$
and
$x-1$.
The area of the small rectangle is
$1\cdot 3=3$
while the area of the big rectangle is
$(x+3)(x-1)=x^2-x+3x-3$
$=x^2+2x-3.$
Now we can determine the area of the given figure:
$(x^2+2x-3)+3=x^2+2x.$
