Which of the following methods would be the easiest to use to solve x2 + 5x - 6 = 0?

All three methods would be easy and effective.

isolating the x2 term and finding the square root of both sides

factoring

using the quadratic formula

For me personally, the easiest way to do this is by isolating the x² term, and finding the square root of both sides. The hardest way (well actually, the longest way) would be to use the quadratic formula. It just complicates things unnecessarily.