When a point moves on the number axis, because the right direction of the number axis is positive, the speed moving to the right is regarded as positive speed, and the speed moving to the left is regarded as negative speed. In this way, the coordinates of the point after moving can be directly obtained by adding the moving distance of the point on the basis of the starting point. That is, the number represented by a point.

How to express the distance between two points on the 1. number axis?

It can be expressed in absolute value, that is, the absolute value of the difference between the numbers represented by two points. For example, if the numbers represented by points A and B on the number axis are A and B, then AB=|a-b| or | B-A |.

2. How to use letters to represent a moving point on the number axis?

It can be solved by addition or subtraction of rational numbers, that is, from the starting point, the moving distance of the moving point is increased and decreased in the positive direction. For example, the number corresponding to point A on the number axis is-1, and point P starts from point A and moves to the right at a speed of 2 unit lengths per second. Let the moving time be t and the number represented by point p be-1+.

3. How to find the midpoint of the line segment between any two points on the axis?

The sum of the numbers represented by two points is divided by two. If the points on the number axis represent numbers A and B, then the number represented by the midpoint of the line segment AB is (a+b)/2.