Simplify the radical expression.

1. 27x^4y^5

2.72m^2n^8

1. sqrt(27x^4y^5) =

sqrt(9*3x^4y^4*y) =
3x^2y^2*sqrt(3y).

2. sqrt(72m^2n^8) =
sqrt(36*2m^2n^8) =
6mn^4*sqrt(2).