Factor by grouping. x2 + 8x + xy + 8y
Don't you see that y is a stranger. So group it -y(x+8) The balance just happens to be x(x+8) So you have these two terms. Take the common factor out. (x+8) (x-y) now that's the answer. Easy ...
= x(x + 8) - y(x + 8) = (x - y)(x + 8)
