等差數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620117481.png)
中,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620132531.png)
, 數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620148491.png)
是等比數(shù)列,且
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620226462.png)
,則
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620241443.png)
的值為
.
試題分析:因為等差數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620117481.png)
中,
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620132531.png)
,所以
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620288673.png)
.又
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620226462.png)
.所以在等比數(shù)列
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620148491.png)
中
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824042620319680.png)
.
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