直接用a(n)=S(n)-S(n-1)就可以,注意此時(shí)n>=2,所以要單獨(dú)算出a(1).
所以a(n)=2n^2-3n+1 -2(n-1)^+3(n-1)-1=4n-5(n>=2).又n=1時(shí),a(1)=S(1)=2-3+1=0,所以:n=1時(shí),a(1)=0;n>=2時(shí),a(n)=4n-5
Sn=2n^2-3n+1 ,a(n)=
Sn=2n^2-3n+1 ,a(n)=
數(shù)學(xué)人氣：846 ℃時(shí)間：2020-04-01 07:14:15
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