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

$= {x}^{2} + 2 x y + {y}^{2}$
$\left(x + y\right) \left(x + y\right)$
$= {\left(x + y\right)}^{2}$
$= {x}^{2} + 2 x y + {y}^{2}$