Question 171478
(-7x^2 + 5xy - 2y^2) + (3x^2 - 5xy - 4y^2)

We are adding two polynomials here.

We combine like terms all the way through.

-7x^2 + 3x^2 + 5xy - 5xy - 2y^2 - 4y^2

Notice that I placed all like terms together.

Simplify part by part.

-7x^2 + 3x^2 = -4x^2

5xy - 5xy = 0

- 2y^2 - 4y^2 = -6y^2

We put it all together and get -4x^2 - 6y^2

Of course, we can factor -4x^2 - 6y^2.

I'll let you that.

If cannot, then write back.