题目内容
已知函数
,其中
.
(Ⅰ)当
时,求曲线
在点
处的切线方程;
(Ⅱ)求f(x)的单调区间.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842279943.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842294389.png)
(Ⅰ)当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842310339.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842326573.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842341495.png)
(Ⅱ)求f(x)的单调区间.
(Ⅰ)
(Ⅱ)① 当
时, 单调递减区间为
;单调递增区间为
,
.②当
时,
的单调递减区间为
,
;单调递增区间为
,
③ 当
时,
为常值函数,不存在单调区间.④当
时,
的单调递减区间为
,
;单调递增区间为
,
.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842357671.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842357349.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842404527.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419460.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842450660.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842482571.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842497371.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842528392.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842482571.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842450660.png)
(Ⅰ)解:当
时,
,
.………………2分
由于
,
,
所以曲线
在点
处的切线方程是
. ………………4分
(Ⅱ)解:
,
. ………………6分
① 当
时,令
,解得
.
的单调递减区间为
;单调递增区间为
,
.……………8分
当
时,令
,解得
,或
.
② 当
时,
的单调递减区间为
,
;单调递增区间为
,
………………10分
③ 当
时,
为常值函数,不存在单调区间.………………11分
④ 当
时,
的单调递减区间为
,
;单调递增区间为
,
.………………13分
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842310339.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842638825.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842653978.png)
由于
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842653569.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842684598.png)
所以曲线
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842326573.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842341495.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842357671.png)
(Ⅱ)解:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240408427311165.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842747376.png)
① 当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842357349.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842778556.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842794344.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842404527.png)
当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842856373.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842778556.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842794344.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842903492.png)
② 当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419460.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842450660.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842482571.png)
③ 当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842497371.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
④ 当
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842528392.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842419463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842388434.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842482571.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842372501.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824040842450660.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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