已知数列{an}中,前n项和为Sn,点(an+1,Sn+1)在直线y=4x-2,
题型:解答题
问题:
已知数列{an}中,前n项和为Sn,点(an+1,Sn+1)在直线y=4x-2,其中n=1,2,3…,
(Ⅰ)设bn=an+1-2an,且a1=1,求证数列{bn}是等比数列;
(Ⅱ)令f(x)=b1x+b2x2+…+bnxn,求函数f(x)在点x=1处的导数f′(1)并比较f′(1)与6n2-3n的大小.
已知数列{an}中,前n项和为Sn,点(an+1,Sn+1)在直线y=4x-2,其中n=1,2,3…,
(Ⅰ)设bn=an+1-2an,且a1=1,求证数列{bn}是等比数列;
(Ⅱ)令f(x)=b1x+b2x2+…+bnxn,求函数f(x)在点x=1处的导数f′(1)并比较f′(1)与6n2-3n的大小.