Answer
The GCF is not $4$, it is $4x$. The factorization is not complete
Result: $4x(x+3)(x^{2}+2)$
Work Step by Step
The GCF is not $4$, it is $4x$. The factorization is not complete
$4x^{4}+12x^{3}+8x^{2}+24x=$
...factor out the GCF.
$=4x(x^{3}+3x^{2}+2x+6)$
...factor by grouping.
$=4x[x^{2}(x+3)+2(x+3)]$
...factor again.
$=4x(x+3)(x^{2}+2)$
