#### Answer

3$x^{3}$ + 2$x^{2}$ - 9x +7

#### Work Step by Step

(2$x^{2}$- 6x+ 7) + (3$x^{3}$ -3x)
The like terms are 2$x^{2}$ , 3$x^{3}$ , -6x and -3x (both containing x) and the constant terms 7.
We begin by grouping these pairs of like terms.
= 2$x^{2}$ + 3$x^{3}$ +(-6x -3x)+ 7
= 3$x^{3}$ + 2$x^{2}$ - 9x +7