# How do you add #(2x^2 - 4xy + y^2) + ( -6x^2 - 9xy - y^2) + (x^2 + xy - 6y^2)#?

##### 1 Answer

#### Explanation:

When adding terms in polynomials, you are allowed to combine "like terms".

Two terms are "like" if they have the same variable(s) with possibly different constant coefficients. Recall that in a term like

For some examples, *not* like terms, because one has a variable of

If you have two "like terms", you add them (or subtract them) by adding (or subtracting) their coefficients. So

Now to the problem at hand. We have:

To make things more clear, we'll rearrange the terms (keeping their positive or negative signs) so that like terms are next to one another.

Now we just add the coefficients.

Now there are no two like terms, meaning we are done adding. This is our final answer.