1212If x > 0 and y > 0, which of the following expressions is equivalent to ?

1212Since x > 0 and y > 0, x can be rewritten as and y can be rewritten as . It follows, then, that can be rewritten as
Because the numerator is a difference of two squares, it can be factored as . Finally, dividing the common factors of \[(\sqrt x - \sqrt y )\] in the numerator and denominator yields .