Need Help Maths !!!

Question

Solve​x2 − 5x − 36 = 0

Show clear algebraic working.

Answer 1

So, we need 2 factors of -36 that add up to -5.

2 and -18? No.

3 and -12? No.

4 and -9? There we go.

x² + 4x - 9x - 36 = 0

x(x + 4) - 9(x + 4) = 0

(x - 9)(x + 4) = 0

x - 9 = 0

x = 9

x + 4 = 0

x = -4