Simplify: (3x^2 - 5xy + 2y^2) - (7x^2 - 3xy - 3^2)

-4x^2 - 2xy + 2y^2 + 9

Step-by-step explanation:

First, perform the indicated multiplications: Multiply each 7x^2, - 3xy and - 3^2 by - 1:

If this is done properly, we get: - 7x^2 + 3xy + 9

Now rewrite (3x^2 - 5xy + 2y^2) - (7x^2 - 3xy - 3^2) as

3x^2 - 5xy + 2y^2 - 7x^2 + 3xy + 9)

Combining the x^2 terms, we get:

-4x^2 - 5xy + 2y^2 + 3xy + 9.

Combining the xy terms, we get:

-4x^2 - 2xy + 2y^2 + 9

This is the final answer (sum), since none of these four terms can be combined.