The domain of f(x) = √(4 - x2) / √(x2 - 1) is given by the interval

The answer is E) [-2 , -1) U (1 , 2]

I found the domain of the top and bottom. Top was -2<x<2 (greater than or equal to)

and for the bottom x>1 or x<-1

If x is greater than 1, then it has to be 2, and if x is less than -1, then it has to be -2, right? I am a tad confused.