Simplify (-7x^2+7x^3)+(-9x^3+9+3x^2)

$(- 7 x^{2} + 7 x^{3}) + (- 9 x^{3} + 9 + 3 x^{2})$

Remove parentheses.

$- 7 x^{2} + 7 x^{3} - 9 x^{3} + 9 + 3 x^{2}$

Add $- 7 x^{2}$ and $3 x^{2}$ .

$7 x^{3} - 9 x^{3} + 9 - 4 x^{2}$

Subtract $9 x^{3}$ from $7 x^{3}$ .

$- 2 x^{3} + 9 - 4 x^{2}$

Move $9$ .

$- 2 x^{3} - 4 x^{2} + 9$