99 points

add the following polynomials. write answer in descending powers of x.

-4x^2+3xy-y^2

-7x^2-xy+6y^2

x^2+4xy-2y^2

-10x^2 + 6xy + 2y^2

Step-by-step explanation:

Wow that's a lot of points! :o

Whenever you add polynomials, you will always be combining like terms. Even when adding three polynomials. So lets lay this out:

-4x^2+3xy-y^2 + -7x^2-xy+6y^2 + x^2+4xy-2y^2

It seems like every polynomial has one part of it that matches the other two polynomials. You can just look at each term of the first polynomial to find what you should be looking for. Like this:

-4x^2 - looking for x^2

3xy - looking for xy

-y^2 - looking for y^2

You are looking at the variables for each term and seeing if they can match up with the other polynomial(s). So start by combining the x^2's in each polynomial:

-4x^2 - 7x^2 + x^2 = -10x^2

Next the xy's:

3xy - xy + 4xy = 6xy

And finally the y^2's:

-y^2 + 6y^2 - 2y^2 = 2y^2

So you take those three terms and turn them back into a polynomial and you will get:

-10x^2 + 6xy + 2y^2

Hope this helped! ^_^

-10x^2 + 6xy + 2y^2

Step-by-step explanation:

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