Simplify x^2+(-3x-x^2+5)

$x^{2} + (- 3 x - x^{2} + 5)$

Remove parentheses.

$x^{2} - 3 x - x^{2} + 5$

Combine the opposite terms in $x^{2} - 3 x - x^{2} + 5$ .

Subtract $x^{2}$ from $x^{2}$ .

$- 3 x + 0 + 5$

Add $- 3 x$ and $0$ .

$- 3 x + 5$