Answer
C. $7x^{2}$ + 11x + 8
Work Step by Step
Original expression is:
($3x^{2}$ + 6x - 1) + ($4x^{2}$ + 5x + 9)
Simplify the brackets
$3x^{2}$ + 6x - 1 + $4x^{2}$ + 5x + 9
Combine like terms.
$3x^{2}$ + $4x^{2}$ + 6x + 5x + 9 - 1
$7x^{2}$ + 11x + 8