I know that the two bars | | around the expression 2-x and x-2 stand for 'absolute value'.
But how does using | | differ from using simple brackets such as: ( ) or [ ] ?
By definition, |x|=x if x is non-negative, |x|=-x if x<0.
For example, |2|=2, |0|=0, |-2|=2.
In particular, |x|=0 if and ...
Absolute value is discussed.