Bài toán :
Cho $a,b,c$ là các số thực không âm. Chứng minh:
$\frac{1}{\sqrt{a^2+ab+b^2}}+\frac{1}{\sqrt{b^2+bc+c^2}}+\frac{1}{\sqrt{c^2+ca+a^2}}\geq \frac{12+2\sqrt{3}}{3(a+b+c)}$
$\sum \frac{1}{\sqrt{a^2+ab+b^2}}\geq \frac{12+2\sqrt{3}}{3(a+b+c)}$
Started By duongvanhehe, 24-11-2012 - 19:40
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Posted 24-11-2012 - 19:40
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