题目内容
(15分)已知定义在
上的函数
=
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639630527.png)
(Ⅰ)若
,求实数
的取值范围;
(Ⅱ)若
对
上的任意
都成立,求实数
的取值范围;
(Ⅲ)若
在[m,n]上的值域是[m,n](m≠n),求实数
的取值范围
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639567535.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639599447.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639614498.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639630527.png)
(Ⅰ)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639692785.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639708267.png)
(Ⅱ)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639723578.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639567535.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639770266.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639786283.png)
(Ⅲ)若
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639599447.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639786283.png)
解:(1)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639848647.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639879490.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640098560.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640113168.png)
第一问中利用单调性可知,由
解得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639848647.png)
第二问中,由
得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640363692.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146403941921.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640410875.png)
(3)中由于
在
单调递增
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405351120.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405501624.png)
令![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640581655.png)
由
的图像可得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640613828.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640113168.png)
本题也可以转化为根的分布求解,同样给分.
解:(1)由
解得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639848647.png)
(2)由
得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640363692.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146407371804.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640410875.png)
(3)由于
在
单调递增
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405351120.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146409091540.png)
令![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640581655.png)
由
的图像可得![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640613828.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640113168.png)
本题也可以转化为根的分布求解,同样给分.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640129971.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639848647.png)
第二问中,由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639723578.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640363692.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146403941921.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640410875.png)
(3)中由于
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639599447.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639567535.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405351120.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405501624.png)
令
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640581655.png)
由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405971004.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640613828.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640113168.png)
本题也可以转化为根的分布求解,同样给分.
解:(1)由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640129971.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639848647.png)
(2)由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639723578.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640363692.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146407371804.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640410875.png)
(3)由于
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639599447.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214639567535.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405351120.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146409091540.png)
令
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640581655.png)
由
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/201408232146405971004.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640613828.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823214640113168.png)
本题也可以转化为根的分布求解,同样给分.
![](http://thumb.zyjl.cn/images/loading.gif)
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