Answer
$n^2\sqrt [4] {25m^3n^3}$
Work Step by Step
Rewrite the radicand as the product of factors such that you can take the fourth root of certain factors:
$\sqrt [4] {25 • m^3 • n^8 • n^3}$
Take the fourth roots of terms to take them out from under the radical sign:
$n^2\sqrt [4] {25m^3n^3}$
