等差数列{an},{bn}的前n项和分别为Sn,Tn,且Sn/Tn=(2n-1)/(3n+2),则a5/b5

问题描述:

等差数列{an},{bn}的前n项和分别为Sn,Tn,且Sn/Tn=(2n-1)/(3n+2),则a5/b5

S9=9(a1+a9)/2=9a5
T9=9(b1+b9)/2=9b5
所以 a5/b5=S9/T9=17/29