2020版高考数学北师大版(理)一轮复习课件:6.2 等差数列及其前n项和
2020版高考数学北师大版(理)一轮复习课件:6.2 等差数列及其前n项和第4页

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知识梳理

考点自诊

1.已知{an}为等差数列,d为公差,Sn为该数列的前n项和. (1)在等差数列{an}中,当m+n=p+q时,am+an=ap+aq(m,n,p,q∈N+).特别地,若m+n=2p,则2ap=am+an(m,n,p∈N+). (2)ak,ak+m,ak+2m,…仍是等差数列,公差为md(k,m∈N+). (3)Sn,S2n-Sn,S3n-S2n,…也成等差数列,公差为n2d. (4)若{an},{bn}是等差数列,则{pan+qbn}也是等差数列.