a) Cho $a\geq1$; $b\geq1$. CMR: $a\sqrt{b-1}+b\sqrt{a-1}$ $\leq ab $
b) Cho a, b >0.CMR: $\sqrt{a^2-b^2}+\sqrt{2ab-b^2}$$\geq a$
c) Cho a, b, c >0. CMR $a^4+b^4+c^4\geq abc(a+b+c)$
Loga
Sinh Học lớp 12
