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[函数] 关于指对数函数图像问题的一点感想

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覃进波 Posted 2013-9-2 17:19 |Read mode
【看了201 2012新课标12题.jpg 2年全国课标卷理科的12题】

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kuing Posted 2013-9-2 18:06
感想在哪?


PS、大概分 k 讨论一下

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chr93918 Posted 2013-9-2 21:41
这两个函数的图像关于直线y=x对称,要求PQ两点间的最小距离,即可转化为求点P到直线y=x的最小距离,可用导数求解。我们称之为"照镜子”

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kuing Posted 2013-9-2 21:43
回复 3# chr93918

楼主估计想说的只是它们可以香蕉……

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chr93918 Posted 2013-9-2 21:56
当K足够大时,f(x)的图像与x轴相交

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chr93918 Posted 2013-9-2 22:09
构造函数h(x)=f(x)-x,求导后得h(x)的最小值为loga(elna/k),不妨a=e,k=10时最小值小于0,因此f(x)的图像与y=x相交

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