1. Cm: a+b+c \geq \sqrt{ab}+\sqrt{bc}+\sqrt{ca} (a,b,c không âm)
2.Cm: a^{3}+ b^{3}+ c^{3}-3abc= \frac{1}{2}(a+b+c)[(a-b)^{2}+(b-c)^{2}+(c-a)^{2}]
3. Cm: \frac{x^{3}+y^{3}+z^{3}}{3}\geq xyz
4. Cm: \frac{a+b}{2}\geq \sqrt{ab}(a,b\geq 0)
5. Cm: \frac{a+b+c}{3}\geq \sqrt[3]{abc}(a,b,c\geq 0)
6. Cm...