设数列An的前n项和Sn=2An-2^n 求A3,A4 证明A(n+1)-2An为等比
设数列An的前n项和Sn=2An-2^n 求A3,A4 证明A(n+1)-2An为等比
设数列{an}的前n项和Sn=2an-2^n,1;求a3,a4
设数列{An}的前n项和Sn=2a-2n平方.1求a3,a4
数列an的前n项和为Sn,a1=t,2a(n+1)=-3Sn+4 求a2,a3 t为何值an等比
设数列an的前n项和sn=2an-2^n 求a3 a4
设数列{an}的前n项和为Sn,并且满足2Sn=an²+n,an>0.(1)求a1,a2,a3.(2)猜想{a
设数列{an}的前n项和为Sn,a1=1,且3a(n+1)=Sn,(1)求a2,a3,a4及an (2)求a2+a4+·
数列an的前n项和为Sn,Sn+an=-1/2n2-3/2n+1(n属于正自然数).设bn=an+n,证明数列bn是等比
设数列的前an的前n项和为Sn,Sn=2an-2^n(1)求a1,a2,a3(2)证明{an+1-2an}是等比数列(3
设数列{an}的前n项和为Sn,a1=1,Sn=nan-2n(n-1) (1)求a2,a3,a4,并求出数列{an}的通
设数列{an}的前n项和为Sn,且a1=1,Sn=nan-2n(n-1) (1)求a2,a3,a4,并求出数列{an}的
已知数列an的前n项和sn=2an-2^n求a3、a4