a(n+1)=6n+1 bn=3/(6n-5)(6n+1) =1/2*6/(6n-5)(6n+1) =1/2*[(6n+1)-(6n-5)]/(6n-5)(6n+1) =1/2*[1/(6n-5)-1(2006•湖北)已知二次函数y=f(x)的图象经过坐标原点,其导函数为f′(x)=6x-2,数列{an}的前n项和为Sn,点(n,Sn
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