First, the first thing is to be familiar with the coordinate system.

After learning the coordinate system by division, the second stage of junior high school began to learn the coordinate system. Coordinate system is the container of all functions and needs to be reflected in all functions.

Second, learn to express the main points.

In addition, you need to learn to represent points and learn to use abscissa and ordinate to represent the position and characteristics of points. Learn to express the position, movement and characteristics of points.

Third, understand the concept of function.

Understand the concepts of independent variables and dependent variables, and then understand the concept of function. Only by understanding the concept of function can we calculate the function problem.

Fourth, pay attention to practical application.

One of the main purposes of learning function is to establish an effective function model in complex real life and use the knowledge of function to solve problems. This is also the learning advocated by the new curriculum standard, so the new textbook strongly advocates the application and practice of functions.

5. Through sketch and image translation, we understand and make it clear that the characteristics of analytical formula and image are completely corresponding. When solving problems, we should have a picture in our mind. When we see the function, we can reflect the basic characteristics of its image in our mind.

Induction of knowledge points (formulas)-functions in junior high school mathematics.

Discrimination of proportional function;

To judge the proportional function, the test is divided into two steps.

One quantity means another quantity, right?

If you have to look at the values again, you need to be all real numbers.

Distinguishing the proportional function, the measurement can be divided into two steps.

One quantity means another quantity, right or wrong.

If there is, it depends on the value. All real numbers must be there.

Images and properties of proportional function;

Line, passage and origin of proportional function graph.

K is positive one, three, negative two and four, and the changing trend is in the heart.

K is low on the left and high on the right, climbing in the same direction.

K is negative, the left is high and the right is low, and the mountain is one big and one small.