Asked by Mish

A rectangle box has a square base and a height that is one more than three times the length of a side of the base. If the sides of the base are each increased by 2" and height is increased by 3" the volume of the box increases by 531 cubic inches. What are the dimensions of the original box?
Answered by oobleck
the original box was x by x by 3x+1
Now you are told that
(x+2)^2 (3x+1 + 3) = x^2 (3x+1) + 531
find x