solve by factoring?

we have given.
(x+6) (x-2) = 9,
for solving this type of eqn. we have to first make the RHS as 0,
therefore, expanding LHS, we get,

x² -2x + 6x - 12-9 = 0
or,
x² + 4x - 21 = 0
or,
x²+7x-3x-21 = 0
or,
x(x+7)-3(x+7) = 0
(x+7) (x-3) = 0,
therefore
x +7=0 and x-3=0
x= -7 or x= 3,
hence we get two values of x as -7 and 3, answers.

(x + 6)(x - 2) = 9
x*x + 6*x - 2*x - 2*6 = 9
x^2 + 6x - 2x - 12 = 9
x^2 + 4x - 12 = 9
x^2 + 4x = 9 + 12
x^2 + 4x = 21
x^2 + 4x - 21 = 0
(x + 7)(x - 3) = 0

x + 7 = 0
x = -7

x - 3 = 0
x = 3

∴ x = -7 or 3

(x+6)(x-2)=9
x² -2x + 6x - 12 = 9
x² + 4x - 21 = 0
(x + 7)(x - 3) = 0
x = -7 and 3