# How do you multiply (k + 3)(k – 3)?

${k}^{2} - 9$
$\left({x}^{2} - {y}^{2}\right) = \left(x + y\right) \left(x - y\right)$
If we let $x = k$ and $y = 3$
$\left({\left(k\right)}^{2} - {\left(3\right)}^{2}\right) = \left(k + 3\right) \left(k - 3\right)$