The original side length of the kite was 9 inches because as the perimeter was 56 inches if 5 inches was added to each side, 5x4=20, and 56-20=36. The perimeter of the original kite is 36 inches, and as it has 4 equal sides, 36 divided by 4=9 inches per side. Hope it helps!
For this problem, we are going to use the Remainder Theorem. This says that for to be a factor of a polynomial , then . Essentially, it says that is a factor if when you substitute into the polynomial you get a result of 0.
Thus, in our case, when we substitute into the polynomial, we should get an answer of 0 if is a factor of the polynomial. Given this information, we can solve for :