Tìm GTNN

V

vodichhocmai

Mọi người ơi, giúp mình bài này với:
Cho x,y,z>0
tìm min
A=$\frac{1}{4}(x^4+y^4+z^4)+\frac{x}{yz}+\frac{y}{zx}+\frac{z}{xy}$

[TEX]A \ge \frac{3}{4} \sqrt[3]{(xyz)^4}+3\sqrt[3]{\frac{1}{xyz}} [/TEX]

[TEX]A \ge \frac{3}{4} \( \sqrt[3]{(xyz)^4}+ \sqrt[3]{\frac{1}{xyz}}+ \sqrt[3]{\frac{1}{xyz}}+ \sqrt[3]{\frac{1}{xyz}}+ \sqrt[3]{\frac{1}{xyz}} \) \ge \frac{15}{4}[/TEX]
 
M

magiciancandy

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