1 . 若
是函数
的两个不同的零点,且
这三个数可适当排序后成等差数列,也可适当排序后成等比数列,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632244ea6931507f8656e1cc3437d392.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc988de1f5918be9fd8cd17e0d43668f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd8166c82c27bd72e556a2726ba648bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/934d37c81b2266c7b86bcc11afaf5f91.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
2 . 设
是等差数列,
,且
,
,
成等比数列.
(1)求
的通项公式;
(2)求
的前
项和
的最小值;
(3)若
是等差数列,
与
的公差不相等,且
,问:
和
中除第5项外,还有序号相同且数值相等的项吗?(直接写出结论即可)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/083869f0bd8a141af0648abaf21b427a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/855c795aa508e27326ee147de89b456b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c0de2e009f8ab1ba18b9f87ac1085ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28d92279eaad4fd4246f63c4aef7deea.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)求
![](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)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ded779955460cd2e08a4574bd5646dd6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
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