1. Deciphering the sign of absolute value: Deciphering the sign of absolute value according to its basic properties is a common strategy to solve the absolute value problem.
2. Seek the maximum value: multi-letter evaluation can be realized by using the non-negativity of absolute value; Moreover, the multiplicity of absolute values can also be deeply understood here.
3. Prove inequalities: Many inequalities can be proved by absolute triangle inequalities.