Question

求一数学题（等差数列）等差数列{an}{bn}的前n项和S,T,且S/T=3n-1/2n+3,则a8/b8等于?(要求具

Answer 1

将n=15代入上式 等差数列求和公式Sn=n(a1+an)/2

有S15/T15={15(a1+a15)/2} / {15(b1+b15)/2}

={15(2a8)/2} / {15(2b8)/2}=a8/b8

=(3*15-1) / (2*15+3)=4/3