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我们知道,为了表示具有相反意义的量,人们发明了正负数,为了区分正数和负数,人们又在数字前面加上“+”和“-”以示区别.那么“+”和“-”到底是如何表示具有相反意义的量的呢?它们又可以表示什么样的量呢?我们先来看几个现实生活中的问题.
We know that in order to represent quantities that have opposite meanings, people have invented positive and negative numbers. In order to distinguish between positive and negative numbers, people add “+” and “-” in front of the numbers to show the difference. Then “ How do +” and “-” represent quantities that have opposite meanings? What kind of quantities can they represent? Let’s look at a few real-life issues first.