12-13高一下·四川成都·阶段练习
1 . 等差数列
中,
;设数列
的前
项和为
,则![](https://img.xkw.com/dksih/QBM/2013/4/12/1571184111804416/1571184116867072/STEM/9f16053d828946f38c3615973bf08831.png?resizew=37)
______________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/890644ae83ebb3572c3d001a94de0b0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b91adba8efbf964e9e35547b0fd0ea36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://img.xkw.com/dksih/QBM/2013/4/12/1571184111804416/1571184116867072/STEM/9f16053d828946f38c3615973bf08831.png?resizew=37)
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2 . 在等差数列{an}中,若a2+a4+a6+a8+a10=80,则其前11项和为
的值为 ________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ab9deef395f417d9dc720ed427fef61.png)
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3 . 数列
的前n项和为
,则![](https://img.xkw.com/dksih/QBM/2016/10/20/1573085703299072/1573085709172736/STEM/005a401c6b644f28bf094e2621923727.png?resizew=164)
________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4695f7d09c11f1ededdd30ae3ae01b9b.png)
![](https://img.xkw.com/dksih/QBM/2016/10/20/1573085703299072/1573085709172736/STEM/005a401c6b644f28bf094e2621923727.png?resizew=164)
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解题方法
4 . 在等差数列
中,若
,则数列
的前9项和![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc4e70b360f988fdbd92300ab22c4613.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7354ced472476105e17fe958acca949.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc4e70b360f988fdbd92300ab22c4613.png)
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5 . 已知数列
为等差数列,前九项和
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dbd9ff686703cad03aa383e5fec21.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3b75ec86aa0e1fe86f6fdeee4ab26ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dbd9ff686703cad03aa383e5fec21.png)
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6 . 数列
的前n项和为
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/275877231453f0bf73fe15052f5a7dc8.png)
__________
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57c599e7cec6d192fb73218e7882ceca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/275877231453f0bf73fe15052f5a7dc8.png)
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解题方法
7 . 已知等差数列
的前
项和为
,若
,且
,则
的最小值为_________ .
![](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/4ac577f987d768e1a115f2747ec0fd6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c20b3db49566d59fa4160f2ddf26815.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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解题方法
8 . 两个等差数列
和
的前
项和分别为
、
,且
,则
等于___
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.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/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c0aa2cd1976a0ad08b9faab83384d87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae59e2a5fdc981b202b2735d9ce0eaf1.png)
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