·求tn=?Sn=75/4(5^n-1)

·求tn=?Sn=75/4(5^n-1) 若 Sn=75/4(5^n-1) tn=?答案是75（5^n-1). 已知{an}{bn}都为等差数列,前n项的和分别为Sn,Tn,且Sn/Tn=5n/6n+1,求a5/b5. 已知两个等差数列{an},{bn}的前n项的和分别为Sn,Tn.若Sn/Tn=(5n+3)/(2n-1).求an/bn 等差数列an`bn`的前n项和分别为Sn`Tn.若Sn/Tn=(7n+1)/(4n+27),求an/bn 等差数列｛an｝,｛bn｝的前n项和分别为Sn,Tn,An/Bn=(7n+1)/(4n+27) 求Sn/Tn 设等差数列{an},{bn}的前n项和分别是Sn,Tn,且Sn/Tn=7n+2/4n-1求a7/b7 Sn=(n^2)/2+n/2,Tn=1/S1+1/S2+...+1/Sn,求Tn 已知等差数列an,bn的前n项和为Sn和Tn且Sn/Tn=(4n-5)/(7n+1),则a8/b8= {an}是等差数列 S7=7 S15=75 Tn是数列{Sn/n}的前n和 求Tn 已知等差数列an,bn的前N项和为Sn,Tn,且Sn/tn=2n+3/n+5,求a5/b6,令Sn=kn(2n+3),Tn=kn(n+5) 已知正项数列{an}=1,前n项和Sn满足an=根号下Sn+根号下Sn-1(n大于等于2) 求证根号下Sn为等差数列求an通项公式（2）记数列{1/an·an+1}的前n项和为Tn,若对任意的n属于N*,不等式4Tn 等差数列{an}{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,求a5/b5=多少 等差数列{an},{bn}的前n项和分别为Sn与Tn,若Sn/Tn=2n/3n+1,则a10/b10= 求详解, 等差数列an,bn的前n项和分别为sn和tn且sn/tn=3n-1/2n+1,求a3/a4的值 等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,求an/bn的表达式 等差数列{an}、{bn}的前n项和分别为Sn、Tn,若Sn/Tn=2n/3n+1,求an/bn 等差数列｛an｝｛bn｝的前n项和分别为Sn,Tn 若Sn/Tn=2n/3n+1 求a7/b3