#### Answer

$4x(x+3)(x^{2} +2)$

#### Work Step by Step

The polynomial have a common factor of 4x therefore factor out the 4x from all four terms.
$4x( x^{3} + 3x^{2} + 2x + 6)$
Group the first two terms and last two terms together
$4x( (x^{3} + 3x^{2}) +(2x + 6))$
Factor out the GCF from the first two terms and last two terms
$4x( x^{2} (x+3) +2(x + 3))$
The student made the mistake that they only factored out the 4 and not the x from the first four terms.
$4x( x^{2} (x+3) +2(x + 3))$
Take out (x+3) common factor and that gives us
$4x(x+3)(x^{2} +2)$