What is the sum of all real numbers x that are not in the domain of the function
f(x) = 1/(x^2 - 7) + 1/(x^4 - 8) + 1/(x^5 - 9)?
The real numbers not in the domain of the function occur where the denominators on the right-hand side are zero. So, for example, when \(x = \pm \sqrt 7\) the term x2 -7 is zero, so \(x = -7 \text{ and }x=7\) are two values not in the domain of f(x). Can you continue from there?