已知等差数列An的前n项和为Sn,等差数列Bn的前n项和为Tn.且Sn/Tn=2n+3/5n+3...求A9/B9的值
3个回答
a9/b9=(17*(a1+a17)/2)/(17*(b1+b17)/2)=S17/T17=37/87
(a1+a17=2a9 b1+b17=2b9)
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