# How do you factor 4-81w^2?

Jun 16, 2016

$4 - 81 {w}^{2} = \left(2 + 9 w\right) \left(2 - 9 w\right)$

#### Explanation:

We use the identity ${a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)$

Hence $4 - 81 {w}^{2}$

= ${2}^{2} - {\left(9 w\right)}^{2}$

= $\left(2 + 9 w\right) \left(2 - 9 w\right)$