Ta có :\(\frac{a\sqrt{a}+b\sqrt{a}}{\sqrt{ab}}:\)\(\frac{1}{\sqrt{a}-\sqrt{b}}\)=\(\frac{\sqrt{ab}\left(\sqrt{a}+\sqrt{b}\right)}{\sqrt{ab}}.\left(\sqrt{a}-\sqrt{b}\right)\)
=\(\left(\sqrt{a}+\sqrt{b}\right)\left(\sqrt{a}-\sqrt{b}\right)\)= a-b (đpcm)