Answer: (-1,-8)
Explanation:
x^2 + 9x + 8 = 0
x^2 + 9x = -8
Add (9/2)^2 to both sides
x^2 + 9x + (9/2)^2 = -8 + (9/2)^2
(x + 9/2)^2 = -8 + 81/4
(x + 9/2)^2 = -32/4 + 81/4
(x + 9/2)^2 = 49/4
Square root both sides
Sqrt (x + 9/2)^2 = sqrt 49/4
x + 9/2 = plus or minus 7/2
Set x + 9/2 = 7/2:
x + 9/2 = 7/2
x = 7/2 - 9/2
x = -2/2 = -1
Set x + 9/2 = -7/2:
x + 9/2 = -7/2
x = -7/2 - 9/2
x = -16/2 = -8
