Answer
$f\left( x+2 \right)=-3x-2$
Work Step by Step
Substituting $x$ with $
x+2
$ in the given function, $
f(x)=-3x+4
,$ then,
\begin{array}{l}\require{cancel}
f\left( x+2 \right)=-3\left( x+2 \right)+4
\\\\
f\left( x+2 \right)=-3x-6+4
\\\\
f\left( x+2 \right)=-3x-2
.\end{array}