Answer
$3x^2(3x+4)(5x+4)$
Work Step by Step
The given expression is
$3x^2(3x+4)^2+x^3\cdot 2(3x+4)\cdot 3$
$=3x^2(3x+4)^2+6x^3(3x+4)$
Factor out $3x^2(3x+4)$.
$=3x^2(3x+4)[(3x+4)+2x]$
$=3x^2(3x+4)[3x+4+2x]$
Add like terms.
$=3x^2(3x+4)(5x+4)$
Hence, the completely factored form of the given expression is $3x^2(3x+4)(5x+4)$.
