题目内容
(本小题满分12分)(考生注意:本题请从以下甲乙两题中任选一题作答,若两题都答
只以甲题计分)
甲:设数列
的前
项和为
,且
;数列
为等差数列,且![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244391457.gif)
(Ⅰ)求数列
的通项公式
(Ⅱ)若
,
为数列
的前![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244328192.gif)
项和,求![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244437206.gif)
乙:定义在[-1,1]上的奇函数
,已知当
时,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244562706.gif)
(Ⅰ)求
在[0,1]上的最大值
(Ⅱ)若
是[0,1]上的增函数,求实数
的取值范围
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/2014082319224429772.gif)
甲:设数列
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244313267.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244328192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244344215.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244359413.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244375371.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244391457.gif)
(Ⅰ)求数列
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244313267.gif)
(Ⅱ)若
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244422593.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244437206.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244469254.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244328192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/2014082319224450071.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244437206.gif)
乙:定义在[-1,1]上的奇函数
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244531270.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244547326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244562706.gif)
(Ⅰ)求
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244531270.gif)
(Ⅱ)若
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244531270.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244609192.gif)
甲:解:(Ⅰ)由
,…1分
, ………3分
, …………………4分
.……6分
(Ⅱ)数列
为等差数列,公差
,……8分
从而
, …………………………9分
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922447651044.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922447811010.gif)
=![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244796866.gif)
=
………………………………………11分
从而![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244827570.gif)
.…………………………………12分
乙:乙:解:
(Ⅰ)设
……3分
…………5分
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922449211094.gif)
当a≥ 4时,f(x )的最大值为2a-4. …………8分
(Ⅱ)因为函数f(x)在[0,1]上是增函数,
所以
…………10分
…………12分
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244640928.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922446561079.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244671539.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922446871229.gif)
(Ⅱ)数列
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244703263.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244718845.gif)
从而
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244734710.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244749834.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922447651044.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922447811010.gif)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244796866.gif)
=
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244812764.gif)
从而
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244827570.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/2014082319224484372.gif)
乙:乙:解:
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/2014082319224485965.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922448741831.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823192244905690.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922449211094.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922449373271.gif)
当a≥ 4时,f(x )的最大值为2a-4. …………8分
(Ⅱ)因为函数f(x)在[0,1]上是增函数,
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922449521016.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231922449681026.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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