To combine the expression you've provided, we'll identify and combine like terms. The original expression is:
\[
- x^2 + 2y^2 + 2y^2 - 2x^3 - 2x^3 - 7y^2 - 7y^2 - 6y^3 - 4y^3 - 4x^3 \]
Now, let's arrange it and group like terms:
-
Terms with \( x^3 \):
- \(-2x^3 - 2x^3 - 4x^3 = -8x^3\)
-
Terms with \( y^2 \):
- \(2y^2 + 2y^2 - 7y^2 - 7y^2 = 4y^2 - 14y^2 = -10y^2\)
-
Terms with \( y^3 \):
- \(-6y^3 - 4y^3 = -10y^3\)
-
Constant terms and remaining terms:
- \(-x^2\) remains as is.
Now, let's combine everything:
\[ -x^2 - 8x^3 - 10y^2 - 10y^3 \]
Thus, the simplified result of your expression is:
\[ -8x^3 - x^2 - 10y^2 - 10y^3 \]