# How do you factor  16 - 9y^2?

Mar 26, 2016

$16 - 9 {y}^{2} = \textcolor{g r e e n}{\left(4 - 3 y\right) \left(4 + 3 y\right)}$

#### Explanation:

Remember in general that
$\textcolor{w h i t e}{\text{XXX}} \left({a}^{2} - {b}^{2}\right) = \left(a - b\right) \left(a + b\right)$

$16 - 9 y$ can be written as
$\textcolor{w h i t e}{\text{XXX}} {\left(4\right)}^{2} - {\left(3 y\right)}^{2}$

Using $4 = a$ and $\left(3 y\right) = b$ in the general equation
we see that the original expression can be factored as
$\textcolor{w h i t e}{\text{XXX}} \left(4 - 3 y\right) \left(4 + 3 y\right)$