+131 Ok, This is very obsecure but there is a such thing as a cube difference rule.
This falls into the cube difference rule.
If we were to expand (x+y)^3 we would get:
x^3+3x^2y+3xy^2+y^3
You can see the similarities...
Anyway, the answer is (x - 2)^3
Also, you can use the binomial theorem
