What is the simplest form of this expression?

y^2 (-4y^2-7) - 2y^4

First, apply the y^2 to everything in the parenthesis. This should give you:

-4y^4 - 7y^2-2y^4

Next, combine any like terms.

-6y^4-7y^2

You can pull out a - y^2 from the equation.

This results in:

-y^2 (6^2 + 7)

Now you are done!