{an}{bn}都是等差数列,已知An/Bn（各自前n项和）=(5n+3)/(2n-1)

题目

{an}{bn}都是等差数列,已知An/Bn（各自前n项和）=(5n+3)/(2n-1)
则an/bn=?

答案

An=n*a1+n(n-1)*d1/2
Bn=n*b1+n(n-1)*d2/2
An/Bn
=[2a1+(n-1)*d1]/[2a1+(n-1)*d1]
=(5n+3)/(2n-1)
a1=4
b1=0.5
d1=5
d2=2
an/bn
=[4+5(n-1)]/[0.5+2(n-1)]
=(5n-4)/(2n-0.5)