Answer
$(4m^{2}-1)(2m+3)$
Work Step by Step
$8m^{3}=$$2.2.2.m.m.m$ and $12m^{2}=2.2.3.m.m$
Hence, $GCF=$$2.2.m.m=$$4m^{2}$
After Grouping :
$=(8m^{3}+12m^{2})-(2m+3)$
$=4m^{2}(2m+3)-1(2m+3)$
$=(4m^{2}-1)(2m+3)$
This can be further written as : $(2m+1)(2m-1)(2m+3)$
(since $(a^{2}-b^{2})=(a+b)(a-b)$)
