# How do you multiply (5x-1)(5x+1)?

$25 {x}^{2} - 1$
$\left({a}^{2} - {b}^{2}\right) = \left(a + b\right) \left(a - b\right)$
If we let $a = 5 x$ and $b = 1$
$\left({\left(5 x\right)}^{2} - {\left(1\right)}^{2}\right) = \left(5 x + 1\right) \left(5 x - 1\right)$