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分类是一种重要的思想方法,指的是要研究的问题包含多种可能情况,不能一概而就时,我们必须按可能出现的所有情况分别讨论,得出各种情况下相应的结果,并判断其合理性.在解答一些应用题的过程中,你是否会想到分类列方程?下面介绍几例,以引起大家注意.例1小明和小华在学校400米的环形跑道上练习长跑,小明每秒跑7米,小华每秒跑5.5米.若两人同时同地出发,问经过几秒后两人首次相遇?分析:在环形跑道上练习长跑,两人同时同地出发,有两种可能情况:一是背向而跑,另是同向而跑.因此,符合要求的时间有两个.
Classification is an important way of thinking. It means that the questions to be studied contain a variety of possible situations. When they can not be generalized, we must discuss them separately according to all situations that may arise, and draw corresponding results in all cases. To determine its rationality. In the process of answering some of the questions, you will think of classification column equation? Here are a few examples to draw attention to. Example 1 Xiao Ming and Xiaohua 400 meters in the school ring track practice long run, Xiao-Ming Run 7 meters per second, Xiaohua run 5.5 meters per second. If the two at the same time starting with the same, ask after a few seconds after the two met for the first time? Analysis: In the circular track practice long distance running, The possible situation: First, run away from the back, the other is the same run and therefore, to meet the requirements of the time there are two.