dangthanhnhan

cho a,c,b>0.CMR:

$\frac{1}{a}+\frac{2}{b}+\frac{3}{c}\geq \frac{3}{a+b}+\frac{18}{3b+4c}+\frac{9}{c+6a}$

cho x,y z>0 . CMR:

$\frac{2x}{x^6+y^4}+\frac{2y}{y^6+z^4}+\frac{2z}{z^6+x^4}\leq \frac{1}{x^4}+\frac{1}{y^4}+\frac{1}{z^4}$

cho a,b,c$\geq$0 và a+b+c=3.CMR:

$\frac{a}{2a+bc}+\frac{b}{2b+ca}+\frac{c}{2c+ab}\leq 1$

cho a,b,c>0. CMR

$\frac{1}{a+b}+\frac{1}{b+c}+\frac{1}{c+a}+\frac{1}{2\sqrt[3]{abc}}\geq \frac{(a+b+c+\sqrt[3]{abc})^2}{(a+b)(b+c)(c+a)}$

cho a,b,c>o và a+b+c=1. CMR:

 $2(\frac{a}{b}+\frac{b}{c}+\frac{c}{a})\geq \frac{a+1}{1-a}+\frac{b+1}{1-b}+\frac{c+1}{1-c}$