利用中项求和公式是什么?

2024-12-03 06:45:48
推荐回答(2个)
回答1:

等差数列中项求和公式是什么
1、等差数列公式
等差数列公式an=a1+(n-1)d
前n项和公式为:Sn=na1+n(n-1)d/2
若公差d=1时:Sn=(a1+an)n/2
若m+n=p+q则:存在am+an=ap+aq
若m+n=2p则:am+an=2ap
以上n均为正整数
文字翻译
第n项的值an=首项+(项数-1)×公差
前n项的和Sn=首项+末项×项数(项数-1)公差/2
公差d=(an-a1)÷(n-1)
项数=(末项-首项)÷公差+1
2、等差数列中项求和公式
数列为奇数项时,前n项的和=中间项×项数
数列为偶数项,求首尾项相加,用它的和除以2
等差中项公式2an+1=an+an+2其中{an}是等差数列

回答2:

等差数列中项求和公式是什么
1、等差数列公式
等差数列公式an=a1+(n-1)d
  前n项和公式为:Sn=na1+n(n-1)d/2
  若公差d=1时:Sn=(a1+an)n/2
  若m+n=p+q则:存在am+an=ap+aq
  若m+n=2p则:am+an=2ap
  以上n均为正整数
文字翻译
  第n项的值an=首项+(项数-1)×公差
  前n项的和Sn=首项+末项×项数(项数-1)公差/2
  公差d=(an-a1)÷(n-1)
  项数=(末项-首项)÷公差+1
2、等差数列中项求和公式
数列为奇数项时,前n项的和=中间项×项数
  数列为偶数项,求首尾项相加,用它的和除以2
  等差中项公式2an+1=an+an+2其中{an}是等差数列

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