The function \( f \) is defined below. \[ f(x)=\frac{x+4}{x^{2}-64} \] Find all values of \( x \) that are NOT in the domain of \( f \). If there is more than one value, separate them with commas. \( x=\square \)

To find the values of \( x \) that are NOT in the domain of the function \( f(x) = \frac{x+4}{x^2 - 64} \), we need to determine when the denominator is equal to zero since division by zero is undefined. The denominator is \( x^2 - 64 \). We set it equal to zero: \[ x^2 - 64 = 0 \] This can be factored as: \[ (x - 8)(x + 8) = 0 \] From this, we find the values: \[ x - 8 = 0 \quad \Rightarrow \quad x = 8 \] \[ x + 8 = 0 \quad \Rightarrow \quad x = -8 \] Thus, the values of \( x \) that are NOT in the domain of \( f \) are: \( x = 8, -8 \)