若数列{an}的前n项和为Sn=n2,则该数列的通项公式?A.an=2n-1 B.an=2n+1 C.an=-2n-1 D.an=-2n+1

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若数列{an}的前n项和为Sn=n2,则该数列的通项公式?A.an=2n-1B.an=2n+1C.an=-2n-1D.an=-2n+1若数列{an}的前n项和为Sn=n2,则该数列的通项公式?A.an

若数列{an}的前n项和为Sn=n2,则该数列的通项公式?A.an=2n-1 B.an=2n+1 C.an=-2n-1 D.an=-2n+1
若数列{an}的前n项和为Sn=n2,则该数列的通项公式?
A.an=2n-1 B.an=2n+1 C.an=-2n-1 D.an=-2n+1

若数列{an}的前n项和为Sn=n2,则该数列的通项公式?A.an=2n-1 B.an=2n+1 C.an=-2n-1 D.an=-2n+1
A.an=2n-1
Sn=n^2
Sn-1=(n-1)^2
an=Sn-Sn-1
=n^2-(n-1)^2
=n^2-n^2+2n-1
=2n-1