10 задание !!!!!!!!!!!!!!!!!!!!!!!!!!!

Решите задачу:

$\displaystyle \frac{2 \sqrt[3]{a^{2}}- \sqrt[6]{a}*(1+a)}{ \sqrt[6]{a^{7}}- \sqrt[6]{a}}= \frac{2a^{4/6}-a^{1/6}*(1+a)}{a*a^{1/6}-a^{1/6}}= \frac{a^{1/6}(2a^{1/2}-1-a)}{a^{1/6}(a-1)}= \\ \\ = \frac{-a+2a^{1/2}-1}{a-1}=- \frac{a-2a^{1/2}+1}{a-1}=\frac{( \sqrt{a}-1)^{2} }{1-a}; \\ \\ \\ =-\frac{(a^{1/2}-1)^{2}}{(a^{1/2}-1)(a^{1/2}+1)}=\frac{ 1-\sqrt{a}}{ 1+\sqrt{a}};$