The volume of a rectangular prism is equal to x3 + 4x2 + 3x.
what is the longest edge of the prism?
x + 1
x + 3
4x
x3

In order to get the volume of a rectangular prism, the formula would be lxwxh. The volume given above is  x3 + 4x2 + 3x. In this case, 
x*(x^2 + 4x + 3) = l*w*h
x* ( x + 3) * (x + 1) = l*w*h
Based on the dimensions, the longest edge of the prism would be x + 3. The correct answer is the second option. Hope this answer helps.