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数学
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已知数列{an}满足:a1+a2+a3+.+an=n^2,求数列{an}的通项an.
人气:149 ℃ 时间:2019-11-08 16:52:36
解答
由题意,Sn=n^2,则a1=1,
S(n-1)=(n-1)^2=n^2-2n+1,n>=2
an=Sn-S(n-1)=n^2-n^2+2n-1=2n-1,n>=2
由于当n=1时,2n-1=1=a1
所以,an=2n-1,n>=1
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