Answer
9x$^3$+11x$^2$-8
Work Step by Step
Distribute the negative sign to the parentheses and then combine like terms vertically.
$\qquad7x^3+5x^2-3$
$\underline{-(-2x^3-6x^2+5)}$
$\qquad\qquad\downarrow$
$\quad7x^3+5x^2-3$
$\underline{\,+2x^3+6x^2-5}$
$\quad9x^3+11x^2-8$
