You didn't start with an equation, so I'm not sure how you ended up with one...? Was the original exercise actually to find the zeroes of the quadratic by completing the square...? If so, then:
You might want to be a bit more careful when writing out the Quadratic Formula
. For instance, the "2a" is supposed to be under all
of "-b +/- sqrt[b^2 - 4ac]". Thus, you should have gotten "-36/18 = -2" for the first part of the solution, not "-6".