167

a)
\sqrt[4]{81}=\sqrt[4]{3^4}=3
b)
\sqrt[6]{27}=\sqrt[6]{3^3}=3^{\frac{1}{2}}
c)
\sqrt[6]{9}=\sqrt[6]{3^2}=3^{\frac{2}{6}}=3^{\frac{1}{3}}
d)
\frac{\sqrt[3]{9}}{\sqrt{3}}=\frac{1}{\sqrt{3}}\cdot\sqrt[3]{3^2}=3^{-\frac{1}{2}}\cdot3^{\frac{2}{3}}=3^{-\frac{3}{6}}\cdot3^{\frac{4}{6}}=3^{\frac{1}{6}}