Question 943591

How would I complete this factor 12x^3+48x^2+21x?
<pre>
{{{12x^3 + 48x^2 + 21x}}}
{{{3x(4x^2 + 16x + 7)}}} ----- Factoring out GCF, 3x
{{{highlight_green(3x(2x + 7)(2x + 1))}}}