[Toán 8]Cmr

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locxoaymgk

CHO x,y khác 0 CMR : [TEX]\frac{x^2}{y^2}+\frac{y^2}{x^2}\geq \frac{x}{y}+ \frac{y}{x}[/TEX] help me!!!!

Bài này dẽ mà :D!
Do[TEX] \frac{x^2}{y^2}+\frac{y^2}{x^2} \geq 2.[/TEX]
[TEX]\Rightarrow 2(\frac{x^2}{y^2}+\frac{y^2}{x^2})\geq \frac{x^2}{y^2}+1+\frac{y^2}{x^2}+1 \geq 2\frac{x}{y}+2\frac{y}{x}[/TEX]
[TEX] \Rightarrow \frac{x^2}{y^2}+\frac{y^2}{x^2}\geq \frac{x}{y}+ \frac{y}{x}[/TEX]
 
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