# How do you factor by grouping 9x^2 + 3xy + 3x + y?

May 22, 2015

$9 {x}^{2} + 3 x y + 3 x + y$

We can make groups of two to factorise this expression:
$\textcolor{b l u e}{9 {x}^{2} + 3 x} + \textcolor{red}{3 x y + y}$

color(blue)(3x is common to both the terms in the first group, and color(red)(y is common to both the terms in the second group:

We can write the expression as :
$3 x \left(3 x + 1\right) + y \left(3 x + 1\right)$

=color(green)((3x+y)(3x+1) , is the factorised form.