what is the range of root (xsquare-4)?can you show the process?

In the given equation Since x² - 4 is in root ,

So x² - 4 >= 0 , (x-2)(x+2) >= 0 , x = (-inf,-2] U (2,inf)

For x = 2,-2 , Value of the function is 0 and for x = inf,-inf , Value of the function is inf

Range is [0,inf)