Solusi

Dari ketaksamaan AM-GM:

$\large{\frac{\frac{a}{b}+\frac{b}{c}+\frac{c}{a}}{3}}\ge \large{\sqrt[3]{\frac{a}{b}.\frac{b}{c}.\frac{c}{a}}}$

$\large{\frac{a}{b}+\frac{b}{c}+\frac{c}{a}}\ge 3$