已知等差数列{an}的前n项和为Sn,若a1=-8,S6+a5=1.
(1)求数列{an}的通项公式;
(2)若数列bn=2n+1,求数列{|an|·bn}的前n项和Tn.
(1)求数列{an}的通项公式;
(2)若数列bn=2n+1,求数列{|an|·bn}的前n项和Tn.
更新时间:2021-01-02 09:46:57
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【知识点】 错位相减法求和
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解题方法
【推荐1】已知等差数列{an}满足:a1=1,
(n≥2且n∈N*).
(1)求数列{an}的通项公式;
(2)设数列{bn}满足bn=﹣2nan,求数列{bn}的前n项和Sn.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edfc67d450e4ee549746915a292a2042.png)
(1)求数列{an}的通项公式;
(2)设数列{bn}满足bn=﹣2nan,求数列{bn}的前n项和Sn.
您最近一年使用:0次
解答题-问答题
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较易
(0.85)
【推荐2】已知数列
中,
,且
,其中
.
(1)求数列
的通项公式;
(2)设
,求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b13a6e1d671215fc96e4bee3541d1096.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5f184cd771d09c0d5caef132ecc3061.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea4ac187cbb465180e89f38250b3970.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd538086dc589bc794bf3abdbebc31b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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