作业帮高中等差数列题 坐等高人!等差数列{an}前n项和为Sn,am +am+1 +…..+a n+1 =0 (m＜n),则Sm+n =?
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高中等差数列题 坐等高人!等差数列{an}前n项和为Sn,am +am+1 +…..+a n+1 =0 (m＜n),则Sm+n =?
高中等差数列题 坐等高人!
等差数列{an}前n项和为Sn,am +am+1 +…..+a n+1 =0 (m＜n),则Sm+n =?
高中等差数列题 坐等高人!等差数列{an}前n项和为Sn,am +am+1 +…..+a n+1 =0 (m＜n),则Sm+n =?
am +am+1 +…..+a n+1=（n-m+1）（am +a n+1）/2 =0
所以am +a n+1 =a1+a m+n =0
所以Sm+n =（m+n）(a1+a m+n )/2 =0