One good way to see these intervals is to plot the graph of this function. I did this and I will attach a picture of the function just for you to see it better:
See that the function is increasing in the interval:
[tex]\rbrack-\infty,1\lbrack[/tex]
Then after x = -1 it starts decreasing at this interval:
[tex]\lbrack-1,0\rbrack[/tex]
And start increasing again in the interval:
[tex]\lbrack0,1\rbrack[/tex]
After that, the function is constant at y = 1! The '[]' is the x interval of values. Thus, for example, [-1,0] means -1 until zero.
