在等差数列
中,若
,则数列
的前9项的和为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6030a55b5e72678ea0622e03b4477225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
更新时间:2020-12-08 20:32:28
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【推荐2】在等差数列
中,前7项的和
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81e563b8d1da5930696a0e6d17d2d1df.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a39dabf1d2cb4094bd2178576970d29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81e563b8d1da5930696a0e6d17d2d1df.png)
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【推荐1】(1)设曲线
在原点处切线与直线
垂直,则a=______ .
(2)已知等差数列
中,已知
,则
=________________ .
(3)若函数
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03219e60920a3c8405ab1d26f82c0807.png)
__________ .
(4)曲线
与直线
及
轴围成的图形的面积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2335369307a03fcaa05b0028abd603bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfb0ef8e25eccfd45f9ce8d476c23ba6.png)
(2)已知等差数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29518f13a1ebc3fff8181c2d7cfba22f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ed444be8b4eaad4e590082d4db36e4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e51ee184aa375a7d777c3e337780307b.png)
(3)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/292eceac11ed9ba43720ea3d85257434.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03219e60920a3c8405ab1d26f82c0807.png)
(4)曲线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/705743c39b40fc433ebe4884d7a105db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48ae59413ab765cf70ec568055800885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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解题方法
【推荐2】若
是单调递增的等差数列,且
,则数列
的前10项和为_______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d44580d37331c62d5980379c564c56f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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