Find a symbolic relationship for f^1(x)

Question

Find a symbolic relationship for f^-1(x)

f(x)=3√3x

Answer 1

f(x) = 3√(3x)

x = 3√(3f^-1(x))

x / 3 = √(3f^-1(x))

(x / 3)² = 3f^-1(x)

(x / 3)² / 3 = f^-1(x)