You may want to review GCDs of terms first.

Factoring a polynomial means finding things you can multiply
together to give it. For example, you can
factor *x*^{2} + 2*x* by saying that
it's *x* * (*x* + 2). To get that, you just work out the
GCD of all the terms of the polynomial. In this case, there were
two terms, *x*^{2} and 2*x*, and their GCD
is *x*. So that's one of the factors. You can divide by that
to get the other factor, which in this case is *x* + 2. (This
division will always come out evenly; if not then you made a
mistake somewhere.) So you write the answer as *x*(*x* +
2).