Answer:
x = - 3, x = 6
Explanation:
x² - 3x - 18 = 0 ( add 18 to both sides )
x² - 3x = 18
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(-
)x +
= 18 +

(x -
)² =
( take square root of both sides )
x -
= ±
= ±
( add
to both sides )
x =
±

Then
x =
-
=
= - 3
x =
+
= 6