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

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

Remove parentheses.

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

Combine the opposite terms in $x^{2} + 7 x + 2 x^{2} - 7 x$ .

Subtract $7 x$ from $7 x$ .

$x^{2} + 2 x^{2} + 0$

Add $x^{2} + 2 x^{2}$ and $0$ .

$x^{2} + 2 x^{2}$

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

$3 x^{2}$