1. Symbol for judging absolute value.
2. If it is a positive number, change the absolute value sign into brackets, and the sign before the absolute value sign remains unchanged.
If it is a negative number, the absolute value sign is changed to brackets, and the sign before the absolute value sign is also changed.
3. Remove the bracket.
4. Merge similar projects.
Second, the formula simplification method with multiple absolute values.
1. Find zero: make the algebraic sign in each absolute value zero, and find zero (not necessarily two).
2. Segmentation: According to the zero obtained in the first step, the points on the number axis are divided into several segments, so that the positive and negative parts in each absolute value symbol in each segment can be determined.
3. Investigate the problems in each part.
4. Synthesize the situation of each section and get the answer to the question.