题目内容
(本小题满分12分) 已知二次函数
满足条件
,及
.
(1)求
的解析式;(2)求
在
上的最大和最小值.
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243092447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243108482.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243139693.png)
(1)求
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243092447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243092447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243201317.png)
(1)
;(2)
,
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243217634.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243232998.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243248826.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的 最值的研究。
(1)根据已知条件可知,设出函数解析式,然后将已知中f(0)
=1,和f(x+1)-f(x)=2x,代入得到关系式进而求解得到。
(2)根据第一问的结论,结合对称轴和开口方向以及定义域得到最值。
解:(1)设
,则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232342432951240.png)
,而
,所以
,所以
,
,则
,所以
……………………………6分
(2)
,在
上递减,在
上递增,………………8分
所以
,
………………………………12分
(1)根据已知条件可知,设出函数解析式,然后将已知中f(0)
=1,和f(x+1)-f(x)=2x,代入得到关系式进而求解得到。
(2)根据第一问的结论,结合对称轴和开口方向以及定义域得到最值。
解:(1)设
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243279752.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232342432951240.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243310585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243139693.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243357644.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243373426.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243404475.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243420502.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243217634.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243466918.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243482443.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243498425.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243232998.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823234243248826.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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