1、等差数列求和公式:(字母描述)
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/838ba61ea8d3fd1fac412feb3e4e251f94ca5f93?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
其中等差数列的首项为a1,末项为an,项数为n,公差为d,前n项和为Sn。
2、等差数列的通项公式:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/30adcbef76094b36038e963cadcc7cd98c109dc7?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
其中等差数列的首项为a1,末项为an,项数为n,公差为d,前n项和为Sn。
3、等差数列的判定:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/ac4bd11373f0820273891cee45fbfbedaa641bc3?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
4、等差数列的基本性质:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/4afbfbedab64034f57a34fd7a1c379310b551df0?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
扩展资料:
知识点:
等差数列基本公式:
末项=首项+(项数-1)×公差
项数=(末项-首项)÷公差+1
首项=末项-(项数-1)×公差
和=(首项+末项)×项数÷2
末项:最后一位数
首项:第一位数
项数:一共有几位数
和:求一共数的总和