题目内容
已知
,直线
与函数
的图像都相切,且与函数
的图像的切点的横坐标为1.
(1)求直线
的方程及
的值;
(2)若
(其中
是
的导函数),求函数
的最大值;
(3)当
时,求证:
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240201394031401.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139481250.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139684601.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139700447.png)
(1)求直线
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139481250.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139747333.png)
(2)若
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139762773.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139778465.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139793447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139809489.png)
(3)当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139825488.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139856996.png)
(1)
,m=-2
(2)
取得最大值![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139903546.png)
(3)由(Ⅱ)知:当
时,
,即
,结合单调性来证明。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139871443.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139809489.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139903546.png)
(3)由(Ⅱ)知:当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139918453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139934561.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139949572.png)
试题分析:解:(Ⅰ)依题意知:直线
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139481250.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139981572.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139996427.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140074646.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139481250.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139871443.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139481250.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139793447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240201401681756.png)
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140183879.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140199406.png)
(Ⅱ)因为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240201402151011.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140230360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140261812.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139918453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140293557.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140324380.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140339564.png)
因此,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139809489.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140386437.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140402503.png)
因此,当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140417357.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139809489.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139903546.png)
(Ⅲ)当
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139825488.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020140480685.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139918453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139934561.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824020139949572.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240201405421770.png)
点评:主要是考查了函数的单调性以及不等式的运用,属于基础题。
![](http://thumb2018.1010pic.com/images/loading.gif)
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