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解题方法
1 . 已知等差数列
中,
,且
成等比数列,
为数列
的前n项和.
(1)求数列
的通项公式;
(2)若数列
的公差
,求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/738dc67ac3b150252a964d1ffe3dfa63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b3bdf32ca1f4388683b39bd1224cc3f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4ce64685821c3e55c07f151996ca8c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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2 . 已知数列
是公差为
的等差数列,且
成等比数列,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2398f658821ecd05f7cb1c6a286fda0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c42ffe7ab16aba523fa1c7e5998a247a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e843f5c36547fe7e3225956667fb55e.png)
A.4 | B.3 | C.2 | D.1 |
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2020-04-11更新
|
1084次组卷
|
8卷引用:2020届湖南省湘潭市高三下学期第三次模拟考试文科数学试题
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3 . 在△ABC中,内角
所对的边分别为a,b,c.
(1) 若a,b,c三边成等比数列,求
的取值范围;
(2)我们知道,若
,则
.现已知
,请猜测
是锐角还是钝角,并加以证明.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/516983449108347c9bbf5dd2a72ab3dd.png)
(1) 若a,b,c三边成等比数列,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7f693e870d5ccdced6e023cc4f7d621.png)
(2)我们知道,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47bfdb4444c1b0568c30abcb07e711e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d921feede226b9b732d85b69d7a34d46.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4039ce4c81a033babf3c4cb04b683c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0c79f975d766486cd369ca057413e78.png)
您最近一年使用:0次
2018-05-22更新
|
540次组卷
|
2卷引用:湖南省湘潭一中2019-2020学年高三上学期11月月考理科数学试题
12-13高三上·河北衡水·期末
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4 . 双曲线
=1(b∈N)的两个焦点F1、F2,P为双曲线上一点,|OP|<5,|PF1|,|F1F2|,|PF2|成等比数列,则b2=_________ .
![](https://img.xkw.com/dksih/QBM/2012/2/2/1570710208364544/1570710213820416/STEM/30326a73749548f8b39bff8a5a75e5ee.png?resizew=53)
您最近一年使用:0次