1. a,b,c>0 và a+b+c=2017

\(CM:\Sigma\dfrac{2017a-a^2}{bc}\ge\sqrt{2}\left(\Sigma\sqrt{\dfrac{2017-a}{a}}\right)\)

2. cho x,y,z tm: \(x^2+y^2+z^2=3\)

\(CM:8\left(2-x\right)\left(2-y\right)\left(2-z\right)\ge\left(x+yz\right)\left(y+zx\right)\left(z+xy\right)\)

3. a,b,c>0 và \(a^2+b^2+c^2\ge6\)

\(CM:\Sigma\dfrac{1}{1+ab}\ge\dfrac{3}{2}\)