What is the domain of the function

f(x) = (2x - 3)(2x + 5)/((x - 9)(x + 9))

Express your answer as an interval or as a union of intervals.

Any x that makes the denominator = 0 is not in the domain

So

x = 9 and x = -9 are not in the domain

Domain =

(-inf , -9) U (-9, 9) U (9 , inf)