题目内容
已知二次函数
的顶点坐标为
,且
,
(1)求
的解析式,
(2)
∈
,
的图象恒在
的图象上方,
试确定实数
的取值范围,
(3)若
在区间
上单调,求实数
的取值范围.
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622928495.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622943382.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622959522.png)
(1)求
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622928495.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623006266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623021317.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623037562.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623068677.png)
试确定实数
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623084337.png)
(3)若
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622928495.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623130428.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623302283.png)
(1)
;(2)
;(3)
或
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623505770.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623520419.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623552396.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623567374.png)
本试题主要是考查了二次函数的解析式的求解,以及函数图像的位置关系的运用。和单调性的求解。
(1)由已知条件设出二次函数的 顶点式解析式,然后代点坐标求解得到结论。
(2)根据图像横在直线的上方,转化为不等式恒成立问题来解决得到结论。
(3)要使得函数在[a,a+1]上单调,则可知区间在对称轴的一侧即可。
(1)由已知,设
,由
,得
,故![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623505770.png)
(2)由已知,即
,化简得
,
设
,则只要
,
∈![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623021317.png)
由
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623520419.png)
(3)要使函数在
单调,则
或
,则
或
.
(1)由已知条件设出二次函数的 顶点式解析式,然后代点坐标求解得到结论。
(2)根据图像横在直线的上方,转化为不等式恒成立问题来解决得到结论。
(3)要使得函数在[a,a+1]上单调,则可知区间在对称轴的一侧即可。
(1)由已知,设
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623583740.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234622959522.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623630386.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623505770.png)
(2)由已知,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623676851.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623692711.png)
设
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623723800.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623739659.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623006266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623021317.png)
由
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623801951.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623520419.png)
(3)要使函数在
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623130428.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623848415.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623567374.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623552396.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234623567374.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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