When m is greater than or equal to 3, when m is greater than or equal to -2 and less than 3, and when m is less than -2, we mainly require the zero point of the absolute value.

The unified method is that the absolute value is positive, for example: │ A │ = A │-A │ = A

But this a can represent any value of zhi, and when it represents a negative number, the above result is wrong.

So when a is positive, that is, when a≥0, │ a │a│=a A a.

When a is negative, that is, when a is less than or equal to 0, a =-a.

That is, after removing the absolute value sign, no matter what method is used, as long as the number is positive.

Extended data;

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.

(1) To solve the absolute value inequality, we must try to remove the absolute value symbol in the formula and convert it into a general algebraic type to solve it.

(2) There are two main methods to prove absolute inequality:

A remove the sign of absolute value and turn it into the proof of general inequality: method of substitution, discussion method and plate method;

B. Using inequality: In this way, the formula in absolute value should be split and combined, and the formula to be proved should be related to the known formula.

Baidu encyclopedia-absolute value