Question

X^2-9x-36=0, how do I solve this

Answer 1

Factor it out.
(x-12)(x+3)

Proof:
-12+3=-9
-12*3=-36

To find zeros:
x-12=0
x=12

x+3=0
x=-3

Final answers for roots: {-3, 12}

Answer 2

x² - 9x - 36 = 0
x² + 3x - 12x - 36 = 0
x(x+3) - 12(x + 3) = 0
(x+3)(x-12) = 0
x+3 = 0 or x-12 = 0
x = -3 x = 12

Answer: x=-3, x=12