#### Answer

$36$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Use the definition of rational exponents to convert the given expression, $
\sqrt[4]{6^{8}}
,$ to exponential form.
$\bf{\text{Solution Details:}}$
Using the definition of rational exponents which is given by $a^{\frac{m}{n}}=\sqrt[n]{a^m}=\left(\sqrt[n]{a}\right)^m,$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
6^{\frac{8}{4}}
\\\\=
6^{2}
\\\\=
36
.\end{array}