1 00:00:00,000 --> 00:00:01,733 5+(-5) 5加5的相反数-5 2 00:00:00,000 --> 00:00:01,933 也就相当于加上-1725314 3 00:00:00,000 --> 00:00:01,000 又回到0 4 00:00:00,000 --> 00:00:02,266 同样的 -7加上什么数得到0 5 00:00:00,000 --> 00:00:02,466 大家看一下 另一种写法是5-5 6 00:00:00,000 --> 00:00:01,933 如果已处于-7 要加上+7 7 00:00:00,000 --> 00:00:02,400 如果有5个某种东西 拿走5个 8 00:00:00,000 --> 00:00:01,000 将等于0 9 00:00:00,000 --> 00:00:02,133 很久以前就学过 还剩下0 10 00:00:00,000 --> 00:00:01,600 或加上它的相反数 11 00:00:00,000 --> 00:00:02,000 答案来源于相同的思想 12 00:00:00,000 --> 00:00:01,066 假设有数字5 13 00:00:00,000 --> 00:00:01,733 什么数加上5等于0？ 14 00:00:00,000 --> 00:00:03,066 大家可能知道答案了 但我要画出来 15 00:00:00,000 --> 00:00:01,400 假设这有条数轴 16 00:00:00,000 --> 00:00:01,000 0在这儿 17 00:00:00,000 --> 00:00:01,000 我们处于5 18 00:00:00,000 --> 00:00:01,466 从5到0 要向左走5 19 00:00:00,000 --> 00:00:01,666 如果向左走5个单位 20 00:00:00,000 --> 00:00:01,133 也就是加上-5 21 00:00:00,000 --> 00:00:01,333 如果这里加上-5 22 00:00:00,000 --> 00:00:01,066 我们将回到0 23 00:00:00,000 --> 00:00:01,400 大家已经知道了 24 00:00:00,000 --> 00:00:02,000 这也许是常识性的知识 25 00:00:00,000 --> 00:00:03,266 不过有个华丽的词语来概括 加法逆元 26 00:00:00,000 --> 00:00:01,000 写下它来 27 00:00:00,000 --> 00:00:02,666 我想这很可笑 用这么花哨的词 28 00:00:00,000 --> 00:00:02,666 描述这么简单的概念 加法逆元 29 00:00:00,000 --> 00:00:02,266 表示的概念是 如果有个数 30 00:00:00,000 --> 00:00:02,000 加上这个数的加法逆元 31 00:00:00,000 --> 00:00:01,800 很多人称其为相反数 32 00:00:00,000 --> 00:00:02,333 加上这个数的相反数 得到0 33 00:00:00,000 --> 00:00:03,066 因为它们长度相同 大家可以这么看 34 00:00:00,000 --> 00:00:01,266 它们大小都是5 35 00:00:00,000 --> 00:00:02,733 这是从0向右走5 这是从0向左走5 36 00:00:00,000 --> 00:00:01,800 同样的 如果从-3开始 37 00:00:00,000 --> 00:00:01,133 如果从-3开始 38 00:00:00,000 --> 00:00:01,266 已经向左走了3 39 00:00:00,000 --> 00:00:02,666 有人会问 什么数加上-3等于0？ 40 00:00:00,000 --> 00:00:01,066 必须向右走3 41 00:00:00,000 --> 00:00:02,066 向右走3就是向正方向走 42 00:00:00,000 --> 00:00:01,000 要加上+3 43 00:00:00,000 --> 00:00:01,600 如果-3加上+3 得到0 44 00:00:00,000 --> 00:00:02,066 总之 如果有任何一个数 45 00:00:00,000 --> 00:00:01,000 1725314 46 00:00:00,000 --> 00:00:01,000 1725314 47 00:00:00,000 --> 00:00:01,866 这个数加上什么得到0 48 00:00:00,000 --> 00:00:01,600 要向相反的方向走 49 00:00:00,000 --> 00:00:01,000 要向左边走 50 00:00:00,000 --> 00:00:01,400 要减去相同的量 51 00:00:00,000 --> 00:00:01,600 可以加上加法逆元