{an}是等差数列,a3=5,s3=9,若存在bn,让a1b1+a2b2+```anbn=5+(2n-3)*2`(n+1
高中数学数列〔简单〕An=2^(n-1)a1=2.bn=2n-1求tn=a1b1+a2b2.+anbn打错了.an=2^
已知{an}是等差数列,首项a1=3,前n项和为sn,数列{bn}是等比数列,首项b1=1,且a2b2=12,s3+b2
等差数列{an},an=2n-1,等比数列{bn},bn=2n-1,求{anbn}的前n项和.
已知等差数列{An},前n项和为Sn.A3=6,S3=12.求数列{2^(n-1)An}的前n项和Bn.
数列an,bn满足anbn=1,an=n²+3n+2,则bn的前十项之和是?
an}{bn}都是公差为1的等差数列,其首项分别为a1b1,且a1+b1=5 a1b1属于N+.C(n)=A(bn)求{
已知:an=3n-1,bn=2^n,求数列{anbn}的前n项和
数列{an},{bn}满足anbn=1,an=n*n(n的平方)+3n+2,则{bn}的前10项之和为()
等差数列{an},{bn}的前n项和分别为Sn,Tn,若SnTn=2n3n+1,则anbn=( )
数列an,bn满足anbn=1,an=n^2+3n+2,则bn的前n项之和为
设Sn是数列{an}的前n项和,所有项an>0,且Sn=n^2+2n,已知bn=2^n,求Tn=a1b1+a2b2+……
设等差数列an的前n项和为Sn,已知bn=1/Sn,且a3*b3=1/2,S3+S5=21,求bn,bn前n项和Tn.