Answer:
x = -1 or x = -7
Explanation:
x^2 + 8x + 7 = 0
x^2 + 8x + ____ = -7 + ____
To complete the square, we add the square of half of the x-term coefficient to both sides.
x-term coefficient: 8
half of it: 4
square it: 4^2 = 16
We add 16 to both sides.
x^2 + 8x + 16 = -7 + 16
(x + 4)^2 = 9
x + 4 = +/- sqrt(9)
x + 4 = 3 or x + 4 = -3
x = -1 or x = -7