Question

Help me with first one?

Answer 1

@mathmale

Answer 2

\[\left| a \right| \ge 0~is~true.\]
let a=0
|a|=|0|=0
if a is negative ,let a=-x ,where x is positive.
|a|=|-x|=x > 0 ,e.g., |-4|=|4|>0
if a is positive ,then |a|=a>0
so \[\left| a \right| \ge 0\]

Answer 3

So the question asks which property is true? not to solve or put on a number line?