等差数列{an}中a2=8,S6=66.设bn=2/[(n+1)an],Tn=b1+b2+…+bn,
等差数列{an}中a2=8,S6=66.设bn=2/[(n+1)an],Tn=b1+b2+…+bn,
有两个等差数列an,bn,若Sn/Tn=a1+a2+.an/b1+b2+---+bn=3n-1/2n+3,则a13/b1
an=2^n bn=2n Tm=b1/a1+b2/a2+……+bn/an,求Tn
an等差数列 bn前n项和sn满足sn=3(bn-1)/2 且a2=b1 a5=b2 ⑴求an bn通项 ⑵设tn为数列
已知an为等差数列,且a2=-8,若等差数列bn满足b1=-8,b2=a1+a2+a3,求bn的前n项和Tn.
AN=3^(n-1),b1/a1+b2/a2+...+bn/an=n(n+2),求{bn}的前n项和TN.要过程啊.
等差数列{an}中an=2n+1,等比数列{bn}满足b1=a2,b2=a4求{bn}前n项和Sn
两个等差数列{an},{bn},a1+a2+...+an/b1+b2+...+bn=7n+2/n+2,则a5/b5=?
两个等差数列{an},{bn},a1+a2+a3+...+an/b1+b2+b3+...+bn=7n+2/n+3. 则a
两个等差数列{an},{bn},a1+a2+...+an/b1+b2+...+bn=7n+2/n+3,求a7/b7?急,
等差数列{an}中,a2=4,S6=42. (1)求数列的通项公式an; (2)设bn=2 (n+1) an ,Tn=b
已知等差数列{an}中,a2=1,S6=15,数列{bn}是等比数列,b1+b2=6,b4+b5=48,求an通项公式,