等差数列{an}{bn},Sn,Tn分别是前n项和,且Sn/Tn=(7n+1)/(n+3),则(a2+a5+a17+a2
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/22 19:12:31
等差数列{an}{bn},Sn,Tn分别是前n项和,且Sn/Tn=(7n+1)/(n+3),则(a2+a5+a17+a22)/(b8+b10+b12+b16)=
![等差数列{an}{bn},Sn,Tn分别是前n项和,且Sn/Tn=(7n+1)/(n+3),则(a2+a5+a17+a2](/uploads/image/z/18665802-18-2.jpg?t=%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%7Ban%7D%7Bbn%7D%2CSn%2CTn%E5%88%86%E5%88%AB%E6%98%AF%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E4%B8%94Sn%2FTn%3D%287n%2B1%29%2F%28n%2B3%29%2C%E5%88%99%EF%BC%88a2%2Ba5%2Ba17%2Ba2)
A2+A5+A17+A22=(A1+d)+(A1+4d)+(A1+16d)+(A1+21d)=4A1+42d=2(2A1+21d)
同理B8+B10+B12+B16=4B1+42d'=2(2B1+21d')
S22=22A1+(1/2)×22×21d=22A1+231d=11(2A1+21d)
同理T22=11(2B1+21d')
(A2+A5+A17+A22)/(B8+B10+B12+B16)
=[2(2A1+21d)]/[2(2B1+21d')]
=[11(2A1+21d)]/[11(2B1+21d')]
=S22/T22
=(7×22+1)/(22+3)
=31/5
同理B8+B10+B12+B16=4B1+42d'=2(2B1+21d')
S22=22A1+(1/2)×22×21d=22A1+231d=11(2A1+21d)
同理T22=11(2B1+21d')
(A2+A5+A17+A22)/(B8+B10+B12+B16)
=[2(2A1+21d)]/[2(2B1+21d')]
=[11(2A1+21d)]/[11(2B1+21d')]
=S22/T22
=(7×22+1)/(22+3)
=31/5
若两个等差数列{An}和{Bn}的前n项和分别是Sn、Tn,已知Sn/Tn=7n/(n+3),则a5/b4=
若两个等差数列{An}和{Bn}的前n项和分别是Sn、Tn,已知Sn/Tn=7n/(n+3),则a5/a6=
两个等差数列{an}和{bn}的前n项和分别是Sn,Tn,已知Sn/Tn=7n/(n+3),则a5/b5等于?
{an},{bn}是两个等差数列,其前n项和分别为Sn和Tn,且Sn/Tn=(7n+2)/(n+3),则a8/b8=
等差数列,{an},{bn}的前n项和分别是Sn,Tn.若Sn/Tn=2n/3n+1,求a5/b5的值
等差数列{an},{bn}的前n项和分别为Sn,Tn,若Sn/Tn=2n/3n+1,则a5/b5=?
等差数列{An},{Bn}的前n项和为Sn与Tn,若Sn/Tn=2n/3n+1,则A5/B7的值是
已知两个等差数列{an},{bn}的前n项和分别是Sn,Tn,若 Sn/Tn =(2n)/(3n+1),则 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a5/b5=多少
已知等差数列{an}与等比数列{bn}的前N项和分别为Sn,Tn,且a2=b3=12,a5=b4=18
设Sn、Tn分别是等差数列an、bn的前n项和,Sn/Tn=(7n+2)/(n+3),则a6/b5=?
有关等差数列的数学题已知等差数列{an},{bn}的前n项和分别为Sn,Tn,且Sn/Tn=(3n+2)/(2n+1),