Answer
$b(a+2b)(a^2-2ab+4b^2)$
Work Step by Step
Factoring the $GCF=
b
$ results to $
b(a^3+8b^3)
$. Using $a^3+b^3=(a+b)(a^2-ab+b^2)$, or the factoring of the sum/difference of two cubes, then,
\begin{array}{l}
b(a^3+8b^3)
\\=
b[(a)+(2b)][(a)^2-(a)(2b)+(2b)^2)
\\=
b(a+2b)(a^2-2ab+4b^2)
.\end{array}
