Chapter 6 Rational Exponents and Radical Functions - 6.4 Use Inverse Functions - 6.4 Exercises - Skill Practice - Page 443: 38

$$y=\sqrt[4]{\frac{2x}{3}},\:y=-\sqrt[4]{\frac{2x}{3}}$$

Switching the elements of the domain and the range (in other words, the dependent and independent variables), we find that the inverse is: $$x=\frac{3}{2}y^4 \\ y=\sqrt[4]{\frac{2x}{3}},\:y=-\sqrt[4]{\frac{2x}{3}}$$