Tính :
1) $\frac{1}{6}^{\log _62-\frac{1}{2}\log _\sqrt{6}5 }$
2) $\frac{1}{16}^{-0,75}+(0,25)^{-\frac{5}{2}}$ = 40
3) $\left ( \frac{b^2}{a} \right )^{-2}.\left ( \frac{a^2}{b} \right )^{-3}$
4) $\frac{(\sqrt[3]{4a} )^2}{\sqrt[6]{4a} }$
5) $\frac{a^\frac{4}{3}\left ( a^{-\frac{1}{3}}+a^\frac{2}{3}\right )}{a^\frac{1}{4}\left ( a^\frac{3}{4} +a^{-\frac{1}{4}}\right )}$