How do you factor -36x^2 + 36y^2?

May 18, 2016

$- 36 {x}^{2} + 36 {y}^{2} = \textcolor{g r e e n}{\left(- 36\right) \left(x - y\right) \left(x + y\right)}$
$- 36 {x}^{2} + 36 {y}^{2}$
$\textcolor{w h i t e}{\text{XXX}} = \left(- 36\right) \left({x}^{2} - {y}^{2}\right)$
$\textcolor{w h i t e}{\text{XXX}} = \left(- 36\right) \left(x - y\right) \left(x + y\right)$
$\left(- 36\right)$ could be further factored as $\left(- 1\right) \left({6}^{2}\right)$ or $\left(- 1\right) \left({2}^{2} \cdot {3}^{2}\right)$ but I'm not sure there is any point in doing this.