How are both sides of these equations equal to one another?
$(\sqrt[4]{x}-\sqrt[4]{y})\cdot(\sqrt{x^{3}}+\sqrt{y^{3}})\cdot\frac{\sqrt[4]{x}+\sqrt[4]{y}}{x-\sqrt{xy}+y}= (\sqrt[4]{x}-\sqrt[4]{y})\cdot(\sqrt[4]{x}+\sqrt[4]{y})\cdot\frac{\sqrt{x^{3}}+\sqrt{y^{3}}}{x-\sqrt{xy}+y}$
I copied this verbatim from a calculus study guide (I'm trying to teach myself), and I'm confused as to how $(\sqrt{x^{3}}+\sqrt{y^{3}})$ switches places with $\sqrt[4]{x}+\sqrt[4]{y}$