Answer
$-6x^4+7x^2+4x-23$
Work Step by Step
Removing the grouping symbols and then combining like terms, the given expression, $
(-6x^4+3x^2-16)+(4x^2+4x-7)
,$ simplifies to
\begin{array}{l}\require{cancel}
-6x^4+3x^2-16+4x^2+4x-7
\\\\=
-6x^4+(3x^2+4x^2)+4x+(-16-7)
\\\\=
-6x^4+7x^2+4x-23
.\end{array}
