粗人匪兵甲
幼苗
共回答了13个问题采纳率:76.9% 举报
Sn/Tn=(7n+2)/(n+3)
S(2n-1)/T(2n-1)=[7(2n-1)+2]/(2n-1+3)
S(2n-1)/T(2n-1)=(14n-5)/(2n+2)
{[a1+a(2n-1)]*(2n-1)/2}/{[b1+b(2n-1)]*(2n-1)/2}=(14n-5)/(2n+2)
[a1+a(2n-1)]/[b1+b(2n-1)]=(14n-5)/(2n+2)
2an/(2bn)=(14n-5)/(2n+2)
an/bn=(14n-5)/(2n+2)
a6/b6=(14*6-5)/(2*6+2)
a6/b6=79/14
1年前
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