McDougal Littell Algebra 2, Chapter 5, 5.2, Section 5.2, Problem 11

We can solve this using the AC factoring method:
x^2 - 2x - 8
Multiply a by c

1 xx -8
Find factors of -8 that add up to b (-2)
these numbers will be -4 and 2, plug these in as b
x^2 - 4x + 2x - 8
now group:
(x^2 - 4x) + (2x - 8)
Factor out the greatest common factors:
x(x - 4 ) + 2 (x - 4 )

Put the numbers outside in a parentheses together :
(x + 2) (x - 4)
set the numbers outside of the parentheses equal to 0
x + 2 = 0
x = -2
x - 4 = 0
x = 4
To check:
-2^2 - 2(-2) - 8
4 + 4 - 8
8 - 8 = 0
4^2 - 2(4) - 8
16 - 8 - 8
16 - 16 =0