#### Answer

-5$x^{2}$ +9x+11

#### Work Step by Step

(-7$x^{2}$+8x + 3) + (2$x^{2}$+ x +8)
The like terms are -7$x^{2}$ and 2$x^{2}$ containing the same variable to the same power($x^{2}$), as well as 8x and x (both containing x), and the constant terms 3 and 8.
We begin by grouping these pairs of like terms.
=( -7$x^{2}$ + 2$x^{2}$) + (8x + x) + (3+8)
= -5$x^{2}$ +9x+11