Simplify (-2x^2-8x+3)+(-9x^2+x+3)

$(- 2 x^{2} - 8 x + 3) + (- 9 x^{2} + x + 3)$

Remove parentheses.

$- 2 x^{2} - 8 x + 3 - 9 x^{2} + x + 3$

Subtract $9 x^{2}$ from $- 2 x^{2}$ .

$- 11 x^{2} - 8 x + 3 + x + 3$

Add $- 8 x$ and $x$ .

$- 11 x^{2} - 7 x + 3 + 3$

Add $3$ and $3$ .

$- 11 x^{2} - 7 x + 6$