K
kingtiger


Cho a,b,c\geq0. a+b+c=1. Chứng minh:
[tex]\frac{1}{a^2+b^2+c^2} + \frac{1}{ab} + \frac{1}{bc} + \frac{1}{ca}\geq30[/tex]
[YOUTUBE]VuNIsY6JdUw&feature[/YOUTUBE]
[tex]\frac{1}{a^2+b^2+c^2} + \frac{1}{ab} + \frac{1}{bc} + \frac{1}{ca}\geq30[/tex]
[YOUTUBE]VuNIsY6JdUw&feature[/YOUTUBE]