两个等差数列{an}{bn}的前n项和分别为An,Bn且An/Bn=(n-3)/(3n+1)则a6/b6
人气:447 ℃ 时间:2020-07-31 23:20:27
解答
A12=(a1+a12)/2*12=(2a6)/2*12=12a5
同理B12=12b5
a6/b6=A12:B12=84/15
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