Answer:
D
Step-by-step explanation:
Given
x² + 6x - 9 = 0 (add 9 to both sides )
x² + 6x = 9
Using the method of completing the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(3)x + 9 = 9 + 9
(x + 3)² = 18 ( take the square root of both sides )
x + 3 = ± [tex]\sqrt{18}[/tex] = ± [tex]\sqrt{9(2)}[/tex] = ± 3[tex]\sqrt{2}[/tex]
Subtract 3 from both sides
x = - 3 ± 3[tex]\sqrt{2}[/tex] → D
