本小题满分12分)设a、b、c成等比数列,非零实数x,y分别是a与b, b与c的等差中项.
(1)已知①a=1、b=2、c=4,试计算
的值;
②a=-1、b=
、c="-"
,试计算
的值
(2)试推测
与2的大小关系,并证明你的结论.
(1)已知①a=1、b=2、c=4,试计算
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35835e961e34b24135f8940e9b3007ea.png)
②a=-1、b=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/158b045c6172c4178d7aa52083e1489f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35835e961e34b24135f8940e9b3007ea.png)
(2)试推测
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35835e961e34b24135f8940e9b3007ea.png)
12-13高二下·吉林·阶段练习 查看更多[1]
(已下线)2012-2013学年吉林省吉林市十二中高二3月月考文科数学试卷
更新时间:2016-12-02 05:46:23
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【知识点】 等差数列
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解答题-问答题
|
容易
(0.94)
【推荐1】在等差数列
中,
,
.
(1)求数列
的通项公式;
(2)令
,求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe229b24e2d56ff6b491725ceae4ff2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5d99b93c12e83ab84110fa2afd66d6f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2e338f282e35e43868742f706a70f1d.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe229b24e2d56ff6b491725ceae4ff2f.png)
(2)令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99a80b5bc86b9090580f082f33b3092c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bee4464b3b4eb6e52ee02f095aae84f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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解答题-问答题
|
容易
(0.94)
名校
【推荐2】已知等差数列
的前n项和为
,且
,
.
(1)求数列
的通项公式
;
(2)求数列
的前n项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b58721c6afd701af600bb554d8a0b14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5032706dd285c22e149c675da465d9ac.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
您最近一年使用:0次