设等比数列an的公比q =二分之一,前n项和为sn则a4分之s4=
人气:341 ℃ 时间:2020-06-06 15:32:33
解答
S4/a4=[a1(1-q^4)/(1-q)]/(a1q^3)
=(1-q^4)/[(1-q)(q^3)]
=(1-1/16)/(1/16)
=15
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