f(x) =
The denominator cannot equal to 0, so if we set it = 0,
its solution will tell us which values of x are not
part of the domain.
x² - 4 = 0
(x - 2)(x + 2) = 0
x = 2, x = -2.
So the domain cannot contain either of those values of x, but
contains all other values of x, so the domain is
(-oo, -2) U (-2,2) U (2, oo)
Edwin