3/1+3²/1+3³/1+······+3/1的N次方,结果为多少对不起,打错了。是1/3+1/3²+1/3³+······+1/3的N次方,结果为多少1 1 1 1— + — + — + ······ + —————=?3 3² 3³ 3的n次方
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![3/1+3²/1+3³/1+······+3/1的N次方,结果为多少对不起,打错了。是1/3+1/3²+1/3³+······+1/3的N次方,结果为多少1 1 1 1— + — + — + ······ + —————=?3 3² 3³ 3的n次方](/uploads/image/z/1267226-26-6.jpg?t=3%2F1%2B3%26%23178%3B%2F1%2B3%26%23179%3B%2F1%2B%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7%2B3%2F1%E7%9A%84N%E6%AC%A1%E6%96%B9%2C%E7%BB%93%E6%9E%9C%E4%B8%BA%E5%A4%9A%E5%B0%91%E5%AF%B9%E4%B8%8D%E8%B5%B7%EF%BC%8C%E6%89%93%E9%94%99%E4%BA%86%E3%80%82%E6%98%AF1%2F3%2B1%2F3%26%23178%3B%2B1%2F3%26%23179%3B%2B%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7%2B1%2F3%E7%9A%84N%E6%AC%A1%E6%96%B9%EF%BC%8C%E7%BB%93%E6%9E%9C%E4%B8%BA%E5%A4%9A%E5%B0%911+1+1+1%E2%80%94+%2B+%E2%80%94+%2B+%E2%80%94+%2B+%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7%C2%B7+%2B+%E2%80%94%E2%80%94%E2%80%94%E2%80%94%E2%80%94%3D%EF%BC%9F3+3%26%23178%3B+3%26%23179%3B+3%E7%9A%84n%E6%AC%A1%E6%96%B9)
3/1+3²/1+3³/1+······+3/1的N次方,结果为多少对不起,打错了。是1/3+1/3²+1/3³+······+1/3的N次方,结果为多少1 1 1 1— + — + — + ······ + —————=?3 3² 3³ 3的n次方
3/1+3²/1+3³/1+······+3/1的N次方,结果为多少
对不起,打错了。
是1/3+1/3²+1/3³+······+1/3的N次方,结果为多少
1 1 1 1
— + — + — + ······ + —————=?
3 3² 3³ 3的n次方
3/1+3²/1+3³/1+······+3/1的N次方,结果为多少对不起,打错了。是1/3+1/3²+1/3³+······+1/3的N次方,结果为多少1 1 1 1— + — + — + ······ + —————=?3 3² 3³ 3的n次方
3/1+3^2/1+...+3^n/1
=3/1*(1-3^n/1)/(1-3/1)
=2/(1-3^n/1)
令s=1/3+1/3²+1/3³+............+1/3^n
s/3=1/3²+1/3³+............+1/3^n+1/3^(n+1)
s-s/3=1/3-1/3^(n+1)
2s/3=1/3-1/3^(n+1)
s=3/2*[1/3-1/3^(n+1)]
s=1/2(1-*1/3^n)麻烦从新回...
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令s=1/3+1/3²+1/3³+............+1/3^n
s/3=1/3²+1/3³+............+1/3^n+1/3^(n+1)
s-s/3=1/3-1/3^(n+1)
2s/3=1/3-1/3^(n+1)
s=3/2*[1/3-1/3^(n+1)]
s=1/2(1-*1/3^n)
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1
等比数列求前n项和,直接代书上的公式即可;
首项为1/3,公比为1/3