What is each expression in simplest form?

a. (9y^sqrt2x)3/2

b. (27x^6y^9)-1/3

a. (9y^sqrt2x)3/2 = 27y^sqrt2x/2 = 27y^3sqrt2x

b. (27x^6y^9)^-1/3 = 1/(27x^2y^3)