题目内容
(本题满分12分)
已知函数
是实数集R上的奇函数,且
在R上为增函数。
(Ⅰ)求
的值;
(Ⅱ)求
在
恒成立时的实数t的取值范围。
已知函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243072789.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240052431811016.png)
(Ⅰ)求
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243181277.png)
(Ⅱ)求
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243212890.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243228514.png)
(1)a="0(2)" ![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243243449.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243243449.png)
试题分析:解(Ⅰ)函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243072789.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243275487.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243290370.png)
(Ⅱ)由(Ⅰ)得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243306487.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243321922.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243337848.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243321922.png)
则有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243368715.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243384680.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243399169.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243415484.png)
由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243212890.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243228514.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240052434771321.png)
∴有
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243493767.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243415484.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243524500.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243540662.png)
得
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243555874.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243399169.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824005243243449.png)
点评:解决该试题的关键是能利用奇函数在x=0处的导数值为零,得到参数a,同时能结合不等式恒成立,分离参数的思想来求解函数的最值,得到结论,属于基础题。
![](http://thumb.zyjl.cn/images/loading.gif)
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