Answer
$6a^{2}b^{5}$
Work Step by Step
$(1296a^{8}b^{20})^{\frac{1}{4}}$
=$(6^{4}\times a^{8}\times b^{20})^{\frac{1}{4}}$
=$(6^{4})^{\frac{1}{4}}\times(a^{8})^{\frac{1}{4}}\times(b^{20})^{\frac{1}{4}}$
=$6\times a^{2}\times b^{5}$
=$6a^{2}b^{5}$