等差数列{An},{Bn}的前n项和分别为Sn与Tn.若Sn/Tn=2n/(3n+1),则An/Bn=____.

等差数列｛An},{Bn}的前n项和分别为Sn与Tn.若Sn/Tn=2n/(3n+1),则An/Bn=____.
怎么做？

---

Sn/Tn=2n/(3n+1),即
S(2n-1)/T(2n-1)=2(2n-1)/[3(2n-1)+1]=(2n-1)/(3n-1),即斗蔽芹
[A1+A（2n-1）并灶]/[B1+B(2n-1)]=(2n-1)/(3n-1),即
2An/空毕2Bn=(2n-1)/(3n-1),
An/Bn=(2n-1)/(3n-1)

---