((Va+1)/(Va-1) - ((4Va)/(a-1))/(Va-1)/(a+Va) V - корень

Решите задачу:

$( \frac{\sqrt{a}+1}{\sqrt{a}-1}- \frac{4\sqr{a}}{a-1}): \frac{\sqrt{a}}{a+\sqrt{a}} = \frac{(\sqrt{a}+1)^2-4\sqrt{a}}{(\sqrt{a}-1)(\sqrt{a}+1)}\times \frac{\sqrt{a}(\sqrt{a}+1)}{\sqrt{a}-1}= \frac{a+2\sqrt{a}+1-4\sqrt{a}}{\sqrt{a}-1}\times\\\\ \times \frac{\sqrt{a}}{\sqrt{a}-1}= \frac{\sqrt{a}(\sqrt{a}-1)^2}{(\sqrt{a}-1)^2}=\sqrt{a}$