题目内容
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701517540.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701548699.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701548387.png)
(I)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701579346.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701595644.png)
(II)在(I)的结论下,设函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701626664.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701642544.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701657410.png)
(I)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701673995.png)
(II)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701688712.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317017042756.png)
当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701720760.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701735479.png)
(I)依题意:![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701751818.png)
在(0,+
)上是增函数,
对x∈(0,+
)恒成立, …………2分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018441114.png)
…………4分
(II)设![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018761269.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018912646.png)
当t=1时,ym I n=b+1; …………6分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317019223356.png)
当t=2时,ym I n=4+2b …………8分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317019382804.png)
当
的最小值为
…………9分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701751818.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701766370.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701782317.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701798710.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701782317.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018441114.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701860984.png)
(II)设
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018761269.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317018912646.png)
当t=1时,ym I n=b+1; …………6分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317019223356.png)
当t=2时,ym I n=4+2b …………8分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408231317019382804.png)
当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701720760.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823131701735479.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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