Step-by-step explanation:
1.
[tex]0 = {x}^{2} - 7x - 18 \\ 0 = {x}^{2} + 2x - 9x - 18 \\ 0 = x(x + 2) - 9(x + 2) \\ 0 = (x + 2)(x - 9) \\ \\ \\ (x + 2) = 0 \: \: \: \: or \: \: \: \: (x - 9) = 0 \\ \\if \: \:x + 2 = 0 \\x = 0 - 2 \\ x = (- 2) \\ \\ if \: \:x - 9 = 0 \\ x = 0 + 9 \\ x = 9 \\ [/tex]
