Answer
$x^3+7x^2-3x$
Work Step by Step
Step 1. Cut the solid into two rectangular prisms.
Step 2. Find the dimensions of the left prism to be $x, 2x-1, 3$
Step 3. Find the dimensions of the right prism to be $x, x, x+1$
Step 4. The total volume is the sum of the individual volumes; we have
$V=3x(2x-1)+x^2(x+1)=6x^2-3x+x^3+x^2=x^3+7x^2-3x$
