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lephuonghoang90


Cho x,y,z > 0 thỏa mãn: xy+yz+xz = 3. Chứng minh rằng
[tex] \frac{1}{xyz}+\frac{4}{(x+y)(y+z)(z+x)}\geq\frac{3}{2}[/tex]
[tex] \frac{1}{xyz}+\frac{4}{(x+y)(y+z)(z+x)}\geq\frac{3}{2}[/tex]