Simplify (-9-13x+3x^3)-(-x+4x^3-9)

$(- 9 - 13 x + 3 x^{3}) - (- x + 4 x^{3} - 9)$

Simplify each term.

Apply the distributive property.

$- 9 - 13 x + 3 x^{3} - - x - (4 x^{3}) - - 9$

Simplify.

Multiply $- - x$ .

Multiply $- 1$ by $- 1$ .

$- 9 - 13 x + 3 x^{3} + 1 x - (4 x^{3}) - - 9$

Multiply $x$ by $1$ .

$- 9 - 13 x + 3 x^{3} + x - (4 x^{3}) - - 9$

Multiply $4$ by $- 1$ .

$- 9 - 13 x + 3 x^{3} + x - 4 x^{3} - - 9$

Multiply $- 1$ by $- 9$ .

$- 9 - 13 x + 3 x^{3} + x - 4 x^{3} + 9$

Simplify by adding terms.

Combine the opposite terms in $- 9 - 13 x + 3 x^{3} + x - 4 x^{3} + 9$ .

Add $- 9$ and $9$ .

$- 13 x + 3 x^{3} + x - 4 x^{3} + 0$

Add $- 13 x + 3 x^{3} + x - 4 x^{3}$ and $0$ .

$- 13 x + 3 x^{3} + x - 4 x^{3}$

Add $- 13 x$ and $x$ .

$3 x^{3} - 12 x - 4 x^{3}$

Subtract $4 x^{3}$ from $3 x^{3}$ .

$- x^{3} - 12 x$