Complete the square to solve the following quadratic equation: x^2 + 2x - 8 = 0.

A. x = -2, x = 4
B. x = 10, x = -8
C. x = -10, x = 8
D. x = 2, x = -4

1 answer

The given quadratic equation is x^2 + 2x - 8 = 0.

To complete the square, we will add and subtract the square of half of the coefficient of x.

In this case, the coefficient of x is 2, so:

x^2 + 2x - 8 = 0

x^2 + 2x + (2/2)^2 - (2/2)^2 - 8 = 0

x^2 + 2x + 1 - 1 - 8 = 0

(x + 1)^2 - 9 = 0

(x + 1)^2 = 9

(x + 1) = ±√9

x + 1 = ±3

x = -1 ± 3

x = -1 + 3 = 2
x = -1 - 3 = -4

Therefore, the solutions to the quadratic equation x^2 + 2x - 8 = 0 are x = 2 and x = -4.

The correct answer is D. x = 2, x = -4.