# How do you use the difference of two squares formula to factor 25x^2-9 ?

$\left(25 {x}^{2} - 9\right) = \left(5 x - 3\right) \cdot \left(5 x + 3\right)$
$\left({a}^{2} - {b}^{2}\right) = \left(a - b\right) \left(a + b\right)$
In this case $a = 5 x$ and $b = 3$