we have
x2 + 9x + 8
Find the factors
Complete the square
(x^2+9x+81/4)-81/4+8=0
Rewrite as perfect squares
(x+9/2)^2=81/4-8
(x+9/2)^2=49/4
square root both sides
(x+9/2)=(+/-)7/2
x=-9/2(+/-)7/2
so
x1=-9/2+7/2=-1
x2=-9/2-7/2=-8
therefore
x2 + 9x + 8=(x+1)(x+8)
answer is
The factors are
(x+1) and (x+8)