# How do you multiply (x-15y)(x+15y)?

${x}^{2} - 225 {y}^{2}$
$\left({a}^{2} - {b}^{2}\right) = \left(a + b\right) \left(a - b\right)$
If we let $a = x$ and $b = 15 y$
$\left({\left(x\right)}^{2} - {\left(15 y\right)}^{2}\right) = \left(x + 15 y\right) \left(x - 15 y\right)$