1, rational number rational number:

① Integer → Positive integer /0/ negative integer

② Score → Positive/Negative Score

Number axis:

① Draw a horizontal straight line, take a point on the straight line to represent 0 (origin), choose a certain length as the unit length, and specify the right direction on the straight line as the positive direction, and you will get the number axis.

② Any rational number can be represented by a point on the number axis.

(3) If two numbers differ only in sign, then we call one of them the inverse of the other number, and we also call these two numbers the inverse of each other. On the number axis, two points representing the opposite number are located on both sides of the origin, and the distance from the origin is equal.

The number represented by two points on the number axis is always larger on the right than on the left. Positive numbers are greater than 0, negative numbers are less than 0, and positive numbers are greater than negative numbers.

Absolute value:

On the number axis, the distance between the point corresponding to a number and the origin is called the absolute value of the number.

(2) The absolute value of a positive number is itself, the absolute value of a negative number is its reciprocal, and the absolute value of 0 is 0. Comparing the sizes of two negative numbers, the absolute value is larger but smaller.

Operation of rational numbers: addition;

① Add the same sign, take the same sign and add the absolute value.

② When the absolute values are equal, the sum of different symbols is 0; When the absolute values are not equal, take the sign of the number with the larger absolute value and subtract the smaller absolute value from the larger absolute value.

(3) A number and 0 add up unchanged.

Extended data;

Addition operation of rational numbers

Two numbers with the same sign are added, and the absolute value is added with the same sign.

Different symbols increase or decrease, large numbers determine and symbols.

Add up the opposites of each other, and the result is that zero must be remembered well.

Note that "big" minus "small" refers to the absolute value.

Subtraction operation of rational number

Negative is equal to plus negative, and reducing the burden is equal to plus positive.

Symbolic law of rational number multiplication operation

The sign of the same sign is negative and the product of a term is zero.

Baidu encyclopedia-junior high school mathematics