Answer:
x = 4 ±
Step-by-step explanation:
Given
(x - 12)(x + 4) = 9 ← expand the left side using FOIL
x² - 8x - 48 = 9 ( ad 48 to both sides )
x² - 8x = 57
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(- 4)x + 16 = 57 + 16
(x - 4)² = 73 ( take the square root of both sides )
x - 4 = ± ( add 4 to both sides )
x = 4 ±