在等差数列
中,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c2c3dd383919d0757b22b7ad17287ef.png)
_________________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53522b17d28d5bbcf702d8db8f1ca665.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c2c3dd383919d0757b22b7ad17287ef.png)
2013·广东东莞·三模 查看更多[2]
更新时间:2016-12-02 11:28:45
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解题方法
【推荐1】已知
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2903053dcfdf4142a46f37750be31fc1.png)
________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c333a1d8306bc3ae9658fdd352459251.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2903053dcfdf4142a46f37750be31fc1.png)
您最近一年使用:0次
填空题-单空题
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较易
(0.85)
名校
【推荐1】由正数组成的等差数列
和
的前n项和分别为
和
,且
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98904bedbce77c4bb629a97d46beb476.png)
______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2a8b2d5bfbd0ba192a24f49767edeab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98904bedbce77c4bb629a97d46beb476.png)
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【推荐2】已知等差数列
前15项的和
=30,则
=___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/973d17cd50a4905164d29b8449fafd52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/713584cdb80460c0c355bf5d97be11b4.png)
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