1, the number axis can visually represent numbers, and the points on the horizontal number axis correspond to real numbers one by one, that is, each real number can be represented by a point on the number axis.

2. Compare the sizes of real numbers, with 0 as the center, and the number on the right is greater than the number on the left.

3. The imaginary number can also be represented by the vertical number axis perpendicular to the horizontal number axis and with the same origin, thus forming a complex plane with the horizontal number axis.

4. Two mutually perpendicular number axes with the same origin can form a plane rectangular coordinate system; Three mutually perpendicular number axes with the same origin can form a spatial rectangular coordinate system to determine the position of an object.

The number axis has the completeness of numbers, which can represent both rational and irrational numbers (collectively called real numbers) and imaginary numbers. At the same time, a coordinate system can be established to form a relatively strict digital system.

Extended data

The introduction of number axis comes from our real life, such as thermometer. By matching real numbers with points on the number axis, we can study numbers with the help of the number axis. For example, because the right direction is defined as the positive direction, the number on the axis relative to the right is greater than the number on the left, thus solving the problem of the ratio between numbers.

For another example, we can use the number axis to study some numbers with special relationships, such as opposites, which are only different in form. From the number axis, intuitively speaking, the points representing the opposites are located on the left and right sides of the origin, and the distance to the origin is equal, so that we can grasp the relationship between the two opposites.

For example, we study the absolute value of a number. In fact, its essential concept is defined by distance, that is, the distance from the point corresponding to a number on the number axis to the origin is called the absolute value of this number. Since it is defined by distance, the absolute value of a number must be non-negative. Generally, there are two numbers with equal absolute values (except 0), which are opposite to each other on both sides of the origin.

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