题目内容
函数
的定义域为D,若存在闭区间[a,b]
D,使得函数
满足:(1)
在[a,b]内是单调函数;(2)
在[a,b]上的值域为[2a,2b],则称区间[a,b]为y=
的“美丽区间”.下列函数中存在“美丽区间”的是 . (只需填符合题意的函数序号)
①、
; ②、
;
③、
; ④、
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226228.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410226483.png)
①、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410320738.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410351779.png)
③、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410367790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410382966.png)
①③④
试题分析:函数中存在“美丽区间”的定义可知:①
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410320738.png)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410414935.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410429680.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410414935.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410460849.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410367790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410507533.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410523849.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410538540.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824024410382966.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240244105701094.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240244105851080.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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