sn=2n^2-3n+3 求an数列

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sn=2n^2-3n+3求an数列sn=2n^2-3n+3求an数列sn=2n^2-3n+3求an数列1.n>1Sn=2n²-3n+3S(n+1)=2(n+1)²-3(n+1)+3

sn=2n^2-3n+3 求an数列
sn=2n^2-3n+3 求an
数列

sn=2n^2-3n+3 求an数列
1.n>1
Sn=2n²-3n+3
S(n+1)=2(n+1)²-3(n+1)+3
=2n²+n+2
a(n+1)=S(n+1)-Sn=4n-1=4(n+1) -5
an=4n-5
2.n=1
a1=2-3+3=2
所以
an= { 2 ,n=1
{ 4n-5,n>1

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