“ 分类讨论”是一种重要数学思想方法,下面是运用分类讨论的数学思想解决问题的过程,请仔细阅读,并解答题目后提出的三个问题.例:三个有理数a,b,c满足abc>0,求
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的值.
解:由题意得: a, b,c三个有理数都为正数或其中一个为正数,另两个为负数.
①当a,b, c都是正数,即a>0,b>0,c>0时,
则:
=1+1+1=3:
②当a,b, c有一个为正数,另两个为负数时,设a>0, b<0, c<0,
则:
=1+(-1)+(-1)=-1:
综上所述:
的值为3或-1.
请根据上面的解题思路解答下面的问题: