已知数列{an}满足a1=2,a(n+1)-an=a(n+1）*an,则a31=?你是怎么想到要除以a(n+1)an的?a(n+1)-an=a(n+1）*an怎么变成1/a(n+1)-1/an=-1？好像没说重点哦？

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