In mathematics, absolute value or modulus |? x？ | is non-negative, regardless of its sign, that is |x | = x means positive x, | x | = -x means negative x (in this case -x is positive), and | 0 | = 0. For example, the absolute value of 3 is 3, and the absolute value of -3 is also 3. The absolute value of a number can be considered as the distance from zero.

Absolute value is the distance from a point corresponding to a number on the exponential axis to the origin, which is represented by "||". |b-a| or |a-b| represents the distance between the point representing a and the point representing b on the number axis.

The following related properties of absolute value:

(1) The absolute value of any rational number is a number greater than or equal to 0, which is not negative.

(2) There is only one number whose absolute value is equal to 0, which is 0.

(3) There are two kinds of numbers whose absolute values are equal to the same positive number, and these two numbers are opposite or equal.

(4) The absolute values of two opposite numbers are equal.

(5) The absolute value of a positive number is itself.

(6) The absolute value of a negative number is its reciprocal.

(7) The absolute value of 0 is 0.