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追及问题是初一学生在学习列方程解应用题时的一个难点。究其原因,主要是对这类问题中的等量关系把握不住,因而列不出方程。下面就追及问题中的三种类型谈谈如何分析问题中的等量关系。一同地、同向、不同时的追及问题例1 一队学生去校外进行军事野营训练,他们以5公里/小时的速度行进,走了18分钟的时候,学校有一紧急通知要传给队长。通讯员从学校出发,骑自行车以14公里/小时的速度按原路追上去,通讯员用多少时间可以追上学生队伍? 分析设通讯员用x小时可以追上学生队伍用线段图表示这个问题的等量关系。
The problem of catching up is a difficult problem for junior students when they are learning to apply equations. The reason for this is mainly that it is impossible to grasp the equal relationship in this type of problem, and therefore the equation cannot be listed. Let’s talk about how to analyze the equal relationship in the problem by following the three types of problems. Cases of catching up with the same place, same direction, and different situations Example 1 A team of students went outside the school to conduct military camping training. They traveled at a speed of 5 kilometers/hour. When they left for 18 minutes, the school had an emergency notice to pass to the captain. Correspondents from the school, riding a bicycle to catch up with the original road at a speed of 14 km/h, how much time can the correspondent catch up with the student team? Analysts can use x hours to catch up with the student team. relationship.