若两个等差数列{an}{bn}的前n项和分别为An、Bn,且满足An/Bn=(4n+2)/(5n-5)(,则a5+a13)/(b5+b13)的值为 答案是7/8

若两个等差数列{an}{bn}的前n项和分别为An、Bn,且满足An/Bn=(4n+2)/(5n-5)(,则a5+a13)/(b5+b13)的值为 答案是7/8
若两个等差数列{an}{bn}的前n项和分别为An、Bn,且满足An/Bn=(4n+2)/(5n-5)(,则a5+a13)/(b5+b13)的值为 答案是7/8

若两个等差数列{an}{bn}的前n项和分别为An、Bn,且满足An/Bn=(4n+2)/(5n-5)(,则a5+a13)/(b5+b13)的值为 答案是7/8
因为an,bn是等差数列
所以
(a5+a13)/(b5+b13)
=A17/B17
=(4*17+2)/(5*17-5)
=70/80
=7/8
如仍有疑惑,欢迎追问.祝：

设an的公差为d，得
∵a5+a13=(a9-4d)+(a9+4d)=2a9；同理b5+b13=2b9
∴(a5+a13)/(b5+b13)=2a9/2b9=a9/b9
∵An/Bn=(4n+2)/(5n-5)
∴(a5+a13)/(b5+b13)=(4×9+2)/(5×9-5)=38/40=19/20
答案为19/20