# How do you factor 9b^2-36?

May 4, 2015

$9 {b}^{2} - 36$ can be written as ${\left(3 b\right)}^{2} - {\left(6\right)}^{2}$

this is of the form:

${a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)$

here: $a = 3 b$ and $b = 6$

so ,

${\left(3 b\right)}^{2} - {\left(6\right)}^{2} = \left(3 b + 6\right) \left(3 b - 6\right)$

the factorized form of $9 {b}^{2} - 36$ is:

$\left(3 b + 6\right) \left(3 b - 6\right)$