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在正、反比例应用题的教学中,教师要善于引导学生根据正、反比例的概念答题,既要注意它们之间的差异,也要注意它们之间的内在联系。 一、利用与同一事物相关的两道例题创设对比情境,使学生掌握解正、反比例应用题的基本方法。 例1.正比例应用题 题目:一辆汽车2小时行64公里,从甲地到乙地共行驶了5小时。甲乙两地间的公路长多少公里? 分析:路程与时间是两种相关联的变量,速度是定量。因为:路程/时间=速度(一定),所以本题符合y/x=K(一定)的正比例判断式,用正比例方法解。 解:设甲,乙两地间的公路长x公里,根据判断式可得:
In the teaching of positive and inverse proportion of applied questions, teachers should be good at guiding students to answer the conceptual questions based on positive and inverse proportion. They should not only pay attention to the differences between them, but also pay attention to the internal relations between them. First, the use of two cases with the same things related to create a contrasting situation, so that students master the correct, inverse proportion of the basic methods of application questions. Example 1. Proportion application problem Title: A car traveling 64 hours 2 hours, a total of 5 hours driving from a to B. How many kilometers of highway between A and B? Analysis: Distance and time are two related variables, the speed is quantitative. Because: distance / time = speed (a), so the problem is in line with y / x = K (a) positive proportional to determine the solution with a proportional method. Solution: Let A, B between the two roads x km long, according to the judgment can be obtained: