B
bach_nien_hoa


Cho x,y,z > 0, chứng minh rằng:
[tex]\frac{2\sqrt{x}}{x^3 +y^2} + \frac{2\sqrt{y}}{y^3 +z^2} +\frac{2\sqrt{z}}{z^3 +x^2} \leq \frac{1}{x^2}+ \frac{1}{ y^2} + \frac{1}{z^2} [/tex]
[tex]\frac{2\sqrt{x}}{x^3 +y^2} + \frac{2\sqrt{y}}{y^3 +z^2} +\frac{2\sqrt{z}}{z^3 +x^2} \leq \frac{1}{x^2}+ \frac{1}{ y^2} + \frac{1}{z^2} [/tex]