Answer
$(3y+4)(3y-1)$
Work Step by Step
Rewrite $9y$ as $12y-3y$.
$9y^2+9y-4=9y^2+12y-3y-4$
Group the first two terms together and group the last two terms together.
$=(9y^2+12y)+(-3y-4)$
Factor out the GCF in each group.
$=3y(3y+4)+(-1)(3y+4)$
$=3y(3y+4)-(3y+4)$
Factor out $(3y+4)$.
$=(3y+4)(3y-1)$
Hence, the completely factored form of the given expression is $(3y+4)(3y-1)$.
