cho a,b,c>0.c/m
$\frac{x^{4}}{x^{4}+\sqrt[3]{(a^{6}+b^{6})(b^{3}+c^{3})^{2}}} +\frac{b^{4}}{b^{4}+\sqrt[4]{(b^{6}+c^{6})(b^{3}+a^{3})^{2}}}+\frac{c^{4}}{c^{4}+\sqrt[4]{(c^{6}+a^{6})(c^{3}+a^{3})^{2}}}\leq 1$
cho a,c,b>0 thỏa a+b+c=1 c/m
$\frac{1}{ab+2c^{2}+2c}+\frac{1}{bc+2a^{2}+2a}+\frac{1}{ca+2b^{2}+2b}\geq \frac{1}{ab+bc+ca}$