Question

一道关于数列的填空已知{an},{bn}为等差数列,Sn,Tn分别为其前n项和,若Sn/Tn=(2n+3)/(n+1)

Answer 1

a3/b3

=2a3/2b3

=(a1+a5)/(b1+b5)

=[(a1+a5)*5/2]/[(b1+b5)*5/2]

=S5/T5

=(2*5+3)/(5+1)

=13/6