等差数列
前9项的和等于前4项的和.若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
_______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3853c9436915931c399b6b7eea4ff6f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
11-12高一下·广东惠州·阶段练习 查看更多[3]
(已下线)2011-2012学年广东惠阳一中实验学校高一第二学期3月月考理科数学(已下线)2011-2012学年广东惠阳一中实验学校高一第二学期3月月考文科数学新疆昌吉教育共同体2020-2021学年高一下学期期中考试数学试题
更新时间:2016-12-01 18:48:15
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【知识点】 等差中项的应用
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解题方法
【推荐1】已知等差数列
的前
项和为
,且
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6a0b86791fe2592e537ee383dc66160.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/268af20329eba1ff50f259280c64da81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f7fda69e2b32b9ced2239f915fa59b.png)
您最近一年使用:0次
填空题-单空题
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容易
(0.94)
名校
【推荐2】已知
,若
三个数成等差数列,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4162c7d09f970cb77cadacdbe521.png)
__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fc4ab958df6b982075e69f2d1aa337c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4162c7d09f970cb77cadacdbe521.png)
您最近一年使用:0次