The inequality A,b,c >0 và abc =1 CM $a) \frac{1}{\sqrt{2a^2+6a+1}} +\frac{1}{\sqrt{2b^2+6b+1}}+\frac{1}{\sqrt{2c^2+6c +1}} \geq 1 $ b) $ \sum \frac{x}{x^2+x+1} \leq \sum \frac{1}{x+2} $ $c) \sum \sqrt{\frac{2}{a+1}} \leq 3 $ [RIGHT][I][B]Nguồn: MathScope.ORG[/B][/I][/RIGHT] |