题目内容
若二次函数
在区间
内至少存在一数值
,使
,则实数
的取值范围是______________________.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240110569301061.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011056961326.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011056977249.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011056992507.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057008313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057039602.png)
试题分析:∵二次函数f(x)在区间[-1,1]内至少存在一个实数c,使f(c)>0的否定是:对于区间[-1,1]内的任意一个x都有f(x)≤0,∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057055857.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240110570701367.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240110571021127.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057117388.png)
∴二次函数在区间[-1,1]内至少存在一个实数c,使f(c)>0的实数p的取值范围是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057039602.png)
点评:根据二次函数的图象开口方向朝上的抛物线,得到对于区间[-1,1]内的任意一个x都有f(x)≤0时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824011057055857.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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