Cho $ a, b, c$ là 3 cạnh của tam giác. CMR:
$abc\geq \frac{1}{8}\left ( \sqrt[3]{\frac{a}{b}}+ \sqrt[3]{\frac{b}{a}} \right )\left ( \sqrt[3]{\frac{b}{c}}+ \sqrt[3]{\frac{c}{b}} \right )\left ( \sqrt[3]{\frac{c}{a}}+ \sqrt[3]{\frac{a}{c}} \right )\left ( a+ b- c \right )\left ( b+ c- a \right )\left ( c+ a- b \right )$