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trungkien199


(T7)Chứng minh rằng: Nếu $x,y,z>0$ thỏa mãn $\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=4$ thì
$\frac{1}{2x+y+x}\frac{1}{x+2y+z}+\frac{1}{x+y+2x}$ \leq $1$
$\frac{1}{2x+y+x}\frac{1}{x+2y+z}+\frac{1}{x+y+2x}$ \leq $1$
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