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[不等式] 恒成立问题

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lrh2006 posted 2017-2-8 20:41 |Read mode
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想问下这样做对吗?我觉得不对吧。如果不对,应该怎么做,请各位指教。谢谢

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realnumber posted 2017-2-8 22:59
y<0不需要讨论,已知条件中有,如果允许y<0,那么y=-1,-100,..等恒成立不可能了.
删掉y<0部分就可以.

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original poster lrh2006 posted 2017-2-9 15:40
回复 2# realnumber

哦,题目条件是对一切实数x,y.我觉得题目是不是有问题?y<0是不可能的

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realnumber posted 2017-2-11 21:36
回复 3# lrh2006


    恩,应该y>0

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其妙 posted 2017-2-25 23:37
回复 3# lrh2006
y=t,好不?擅自改字母,改了后,有不标注范围

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