Simplify x^2-3x+4+4x^2-x-12

$x^{2} - 3 x + 4 + 4 x^{2} - x - 12$

Add $x^{2}$ and $4 x^{2}$ .

$5 x^{2} - 3 x + 4 - x - 12$

Subtract $x$ from $- 3 x$ .

$5 x^{2} - 4 x + 4 - 12$

Subtract $12$ from $4$ .

$5 x^{2} - 4 x - 8$