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证明there are no natural numbers m and n such that 7/17 = (1/m) + (1/n).

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解决时间 2021-11-20 07:23
  • 提问者网友:爱唱彩虹
  • 2021-11-19 20:31
证明there are no natural numbers m and n such that 7/17 = (1/m) + (1/n).
最佳答案
  • 五星知识达人网友:woshuo
  • 2021-11-19 21:10
m,n are natural numbers, so that (1/m) + (1/n)=(m+n)/mn and we know that 7 can be writen by 1+6,2+5,3+4, by reason of symmetry of m and n,we ignore the other m+n permutations 4+3 5+2 6+1. and 1*6=6 2*5=10 3*4=12 and cant be a multiplier of 17(in fact 17 is premier.)even if m+n=7k mn=17k. note that k is a random positive natural number. we can establish a equation n^2-7kn+17k=0 which dont have natural number as roots.
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