已知等比数列
的公比为2,前4项的和是3,则前8项的和为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
A.48 | B.51 | C.54 | D.57 |
更新时间:2021-08-13 08:47:56
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【推荐1】已知数列
的前n项和为
,若
,
(
),则
等于( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5995ed803c917b995c197681464f2570.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e167b43045b3297248e334c41c621b8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b50ec7342673cc1f11b613c3efd3c6c.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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【推荐2】公元前1650年的埃及莱因德纸草书上载有如下问题:“十人分十斗玉米,从第二人开始,各人所得依次比前人少八分之一,问每人各得玉米多少斗?”在上述问题中,第一人分得玉米( )
A.![]() | B.![]() |
C.![]() | D.![]() |
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【推荐1】在正项等比数列
中,
为其前
项和,若
,则
的值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af1f7fca853018d54694bba9a373b6c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a27c112387e56c976489fa484c0d48f.png)
A.10 | B.20 | C.30 | D.40 |
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【推荐2】若等比数列
的前
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.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/01d8fd5891c242326417692a1721101c.png)
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A.9 | B.6 | C.7 | D.4 |
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