Function knowledge runs through junior high school mathematics, which makes students get into contact with functions initially.

Studied the plane rectangular coordinate system, function concept, linear function (proportional function), let

Students feel the corresponding relationship between function and function image to realize the combination of number and shape.

An important mathematical thinking method. Learning inequalities and inequality groups in the second grade of junior high school, through the connection with linear functions, further permeates the idea of combining numbers with shapes. Learning inverse proportional function and quadratic function in grade three enables students to fully understand and master the relevant knowledge of function and realize the application of mathematical model of function number in real life, so function accounts for junior high school mathematics system.

It has an important position and function, and it is the main line of learning in the field of mathematics and algebra in junior high school.