P
popstar1102


cho a,b,c là ba số dương. chứng minh
$\frac{a}{bc}+\frac{b}{ac}+\frac{c}{ab}$\geq $2(\frac{1}{a}+\frac{1}{b}-\frac{1}{c})$
$\frac{a}{bc}+\frac{b}{ac}+\frac{c}{ab}$\geq $2(\frac{1}{a}+\frac{1}{b}-\frac{1}{c})$