Answer:
The function f(x) = IxI works as follows:
if x ≤ 0, then IxI = -x
if x ≥ 0, then IxI = x
notice that if x = 0, then I0I = 0 = -0
Now, we want that:
IxI = x
Then we have that x must be greater or equal than zero:
x ≥ 0.
To represent it in the number line, you should use a black dot in the zero an shade all the right region:
__-2__-1__0__1__2__3__4__5__6__....
