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2008年南京市中考数学试卷第28题,两列快车在同一车站同一线路同一方向在不同时间出发,与相隔900千米的另一车站的一列慢车在复行线路对向开来并且与第一列快车同一时间出发的路程作为一个变量,慢车行驶的时间作为另一个变量,两变量的函数关系为一次函数,由于把快车、慢车的行驶时间放到了平面直角坐标系的一条折线上,对于初中生来说分析起来略加困难.继南京市此题出现之后,其他省市以该题作为母题加以变式和延伸,出现了很多优秀题目,要弄懂此种类型
In the 28th question of the 2008 Nanjing Mathematical Examination Questionnaire, two express trains set off at the same time and in the same direction at the same station, and a local train at another station separated by 900 kilometers was opposite and opposite to the first. The distance traveled by the express train at the same time is used as a variable. The time when the local train travels is used as another variable. The function relationship between the two variables is a linear function. Since the travel time of express trains and local trains is placed on a polyline in the plane rectangular coordinate system, For students, the analysis is a bit more difficult. Following the emergence of this topic in Nanjing, other provinces and cities have used the title as a motif to be transformed and extended. There have been a lot of outstanding topics. To understand this type