Answer
$-2x^{2} +12x +11$
Work Step by Step
There are two numbers with the variable $x^{2}$ when you add these like terms you get:
$5x^{2} - 7x^{2} = -2x^{2}$
There are two numbers with the variable $x$ when you add these like terms you get:
$4x+8x =12x$
There is only one constant term:
$11$
Add all of these together:
$-2x^{2} +12x +11$