[中學] 不等式

[mater2004 (mater)]

http://ppt.cc/PjmS

麻煩一下

謝謝!

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※ 發信站: 批踢踢實業坊(ptt.cc) 
◆ From: 111.252.85.187
→ suhorng     :|x-y|/|1-xy|<1=>|x-y|<|1-xy|=>x^2-2xy+y^2<
→ suhorng     :1-2xy+(xy)^2=>(xy)^2-x^2-y^2+1>0=>(x^2-1)(y^2-1)>
→ suhorng     :0=>-1<y<1 (x^2-1<0,所以y^2-1<0)