$ab+bc+ca \geq 3$
Cho $a,b,c\geq 0$ thỏa mãn
$ab+bc+ca3.Cm \frac{1}{a^{2}+2} + \frac{1}{b^{2}+2} + \frac{1}{c^{2}+2} \leq 1$
$ab+bc+ca \geq 3$
Cho $a,b,c\geq 0$ thỏa mãn
ab+bc+ca
\geq 3.Cm \frac{1}{a^{2}+2} + \frac{1}{b^{2}+2} + \frac{1}{c^{2}+2} \leq 1$