[คusักคณิm]

1. $\sqrt[3]{81}=(3^4)^\frac{1}{3}=3^\frac{4}{3}$
$\sqrt{27}=(3^3)^\frac{1}{2}=3^{1.5}$
$\frac{\sqrt[3]{81}}{\sqrt{27}}=3^{\frac{4}{3}-1.5}$
$=3^\frac{-1}{6}$
$=\frac{1}{3^\frac{1}{6}}$
$=\frac{1}{\sqrt[6]{3}}$
choice 4