Simplify (3x^3+6x^2-5x+5)+(-2x^3+3x^2-6)

$(3 x^{3} + 6 x^{2} - 5 x + 5) + (- 2 x^{3} + 3 x^{2} - 6)$

Remove parentheses.

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

Subtract $2 x^{3}$ from $3 x^{3}$ .

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

Add $6 x^{2}$ and $3 x^{2}$ .

$x^{3} + 9 x^{2} - 5 x + 5 - 6$

Subtract $6$ from $5$ .

$x^{3} + 9 x^{2} - 5 x - 1$