题目内容
记数列{
}的前n项和为为
,且
+
+n=0(n∈N*)恒成立.
(1)求证:数列
是等比数列;
(2)已知2是函数f(x)=
+ax-1的零点,若关于x的不等式f(x)≥
对任意n∈N﹡在x∈(-∞,λ]上恒成立,求实常数λ的取值范围.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121255347.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121286388.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121286388.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121255347.png)
(1)求证:数列
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121317522.png)
(2)已知2是函数f(x)=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121333337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121255347.png)
(Ⅰ)见解析;(II)
的取值范围
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121364291.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121380913.png)
试题分析:(Ⅰ)利用
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121380485.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121395497.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121411412.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121489937.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121489663.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121520275.png)
试题解析:(Ⅰ)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121520436.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240251215361195.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121551971.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240251215671121.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121583893.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121598339.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121598339.png)
(II)由(Ⅰ)可得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121629762.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240251216611358.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121676914.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121692952.png)
即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408240251217071082.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121723589.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121739717.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121754690.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121770768.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121785790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121801754.png)
即所求
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121364291.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824025121380913.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
题目内容