## Algebra: A Combined Approach (4th Edition)

$(\sqrt{x}-y)(\sqrt{x}+y)=x-y^{2}$
$(\sqrt{x}-y)(\sqrt{x}+y)$ Evaluate this product by using the formula for factoring a difference of squares. The formula is $a^{2}-b^{2}=(a-b)(a+b)$. For this expression, $a=\sqrt{x}$ and $b=y$ Substitute the known values into the formula and simplify if possible: $(\sqrt{x}-y)(\sqrt{x}+y)=(\sqrt{x})^{2}-y^{2}=x-y^{2}$