Write the expression in simplest form. Then supply the missing radicand.

$\displaystyle{\sqrt[{{4}}]{{{4}{{a}}^{{2}}{{b}}^{{40}}{{c}}^{{2}}}}}={{b}}^{{10}}\sqrt{{?}}\usepackage{cmbright}\Huge\$

The missing radicand is _____.

(Write your answer without any exponents.)