Teaching purpose: 1, can use known conditions to find the correlation value. 2. Use equation knowledge to solve practical problems. 3. By solving practical problems, improve the awareness and ability of mathematics application, and further cultivate students' interest in learning. Teaching emphasis: column algebra. Teaching difficulty: column equation. Teaching method: heuristic. Teaching process: 1. Problem situation. The bus company wants to add a stop between building 1 and building 2. 1 Building has a daily passenger flow of about 100 people, and Building 2 has a daily passenger flow of about 50 people. The distance between the two buildings is 600 meters. (transition textbook p 10 page) second, the solution of the problem. (1) If the distance from the station to Building 2 is x meters, it is correct to express the sum of the distances from all passengers on two floors to the station as () meters by algebraic expression. A, 50 b, 100× (600-x) c, 50x+ 100(600-x)(2) Fill in the form.

X/ meter

100

200

300

celebrity

500

600

All passengers

Distance to the station

Sum/meter

60000

55000

30000(3) What pattern did you find? (The closer the station is, the smaller the building 1 is. (4) It is suggested that the station be located in Building 1. Although the total distance is the smallest, it is unfair for the passengers in Building 2 to go too far, so the bus company puts forward the following two schemes: Scheme 1: The station is located in the middle of two buildings, that is, X = 300. At this time, the sum of the distances between 1 and 1 is greater than that of Building 2. Scheme 2: Set the station location according to the sum of the distances from all passengers in Building 1, which is equal to the sum of the distances from all passengers in Building 2 to the station. Where should the station be located? It is expressed by algebraic expression: the sum of the travel distances of all passengers in 1 building to the station is meters. The total distance from all passengers in Building 2 to the station is meters. According to the company's requirements, the listed equation is: x= so the bus stop should be located at a distance of meters from Building 2. Thinking: 1. Is it reasonable to set up a station like this? Why? 2. If there is no station x meters away from 1 building, how to do the equation? Just try it. Where is the milk station?

1

Haolou

2

Haolou

a

Haolou

Milk station 100800χ m

Number of households ordering milk

West Zone 1 Building

80

West zone building 2

70

East zone a building

120 set up a milk station to facilitate the residents of the above three buildings to get milk. The milk company thinks that the setting of the milk collection station should conform to the following principle: the sum of the daily distances from all milk collectors in the east (Building A) is equal to the sum of the daily distances from all milk collectors in the west (Building 1 and Building 2). The milk station is x meters away from Building A in the East Zone. Please find X. ..