Chapter 0 - Before Calculus - 0.4 Inverse Functions - Exercises Set 0.4 - Page 45: 13

$\ y=\ \sqrt{\frac{3}{x}}\ or\ y=\ -\sqrt{\frac{3}{x}}\\$

$\ The\ given\ function\ is\ y=\frac{3}{x^{2}}\\ \ Interchanging\ the\ variables\ x\ and\ y\ we\ get\ ,\\ \ x=\frac{3}{y^{2}}\\ \ y^{2}=\frac{3}{x}\\ \ Taking\ the\ square\ root\ on\ both\ sides\ we\ get\ ,\\ \ y=\ \sqrt{\frac{3}{x}}\ or\ y=\ -\sqrt{\frac{3}{x}}\\$