Question

What is the answer to this

Answer 1

${x}^{2} - 9x - 36 = 0 \\ (x - 12)(x + 3) = 0 \\ x - 12 = 0 \\ x = 12 \\ x + 3 = 0 \\ x = - 3$

Answer 2

X^2 - 9x - 36 = 0

Note that one possible set of factors is (x-12)(x+3).  Why?  Because (-12)(3) = -36 and -12x + 3x = -9x.