用等比数列,公比是1/3,这是前六项的和故总和=1/3{1-(1/3)^6}/(1-1/3)即可
1/3+1/9+1/27+1/81+1/243+1/729
3个回答
相关问题
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1+3+9+27+81+243+729
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1-1/3-1/9-1/27-1/81-1/243-1/729=?
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计算：1+1/3+1/9+1/27+1/81+1/243+1/729
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1-1/3-1/9-1/27-1/81-1/243-1/729-1/2187
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1-[2/3]-[2/9]-[2/27]-[2/81]-[2/243]-[2/729]=______．
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1、-3,9 ,-27,81,-243,729,...2、0,12,-24,84,-240,732,.
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①-3,9,-27,81,-243,729,...②0,12,-24,84,-241,732,...③-1,3,-9,2
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观察下面的数（1)3,9,27,81,243,729,...（2)1,7,25,79,241,727,...(3)1,3
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用错位相减法算 （1）3+9+27+81+243+729+2187的和
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初中数学题啊,紧急啊!~~3.9.27.81.243.729…………1.7.25.79.241.727…………1.3.9