## College Algebra (10th Edition)

The domain of the function is all real numbers, except for when the denominator is 0. Thus, we let the denominator equal 0: $$x^2+4 = 0 \\ x= \sqrt{-4}$$ Because the square root of a negative number is not a real value, we see that the denominator will never equal 0. Thus, the domain is the set of all real numbers.