[(3x^2y^3)^2]3
work from the inside out
(3x^2y^3)^2
3^2 (x^2)^2 (y^3)^2
x^2^2 multiply the exponents =x^4
y^2^3 = y^6
9 x^4 y^6
[9x^4 y^6]^3
9^3 x^4^3 y^6^3
729 x^12 y^18
