qqlovefly
幼苗
共回答了19个问题采纳率：94.7% 举报
sa(2n-1)/sb(2n-1)=[3(2n-1)+5]/[2(2n-1)-3]
{[a1+a(2n-1)]*(2n-1)/2}/{[b1+b(2n-1)]*(2n-1)/2}=[6n-3+5]/[4n-2-3]
[a1+a(2n-1)]/[b1+b(2n-1)]=(6n+2)/(4n-5)
2an/2bn=(6n+2)/(4n-5)
an/bn=(6n+2)/(4n-5)
a6/b6
=(6*6+2)/(4*6-5)
=38/19
=2
1年前
1
赞
