Answer
$( z-4)(3z^2+2)$.
Work Step by Step
The given polynomial is
$=3z^3+2z-12z^2-8$
$=3z^3-12z^2+2z-8$
Group the terms.
$=(3z^3-12z^2)+(2z-8)$
Factor each group.
$=3z^2(z-4)+2(z-4)$
Factor out $(z-4)$.
$=( z-4)(3z^2+2)$
Hence, the complete factor of the polynomial is $( z-4)(3z^2+2)$.
