x(x - 8) + (x - 8)
First we need to get rid of the brackets to get the equation in the normal form:
x^2 - 8x + x - 8
x^2 - 7x - 8
Now we need to think about factors of 8 that would work :
8 = 8x1 = 2x4
In this case, after considering these factors, we can see that -8 and 1 are the only solutions that will give us -7. So,
x(x - 8) + (x - 8) = (x - 8)(x + 1)
You can check that this is the answer by multiplying out the brackets:
(x - 8)(x + 1) = x^2 + x - 8x - 8 = x^2 - 7x - 8