Simplify (x^3+2x^2-4)+(3x^2+6)

$(x^{3} + 2 x^{2} - 4) + (3 x^{2} + 6)$

Remove parentheses.

$x^{3} + 2 x^{2} - 4 + 3 x^{2} + 6$

Add $2 x^{2}$ and $3 x^{2}$ .

$x^{3} + 5 x^{2} - 4 + 6$

Add $- 4$ and $6$ .

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