# How do you simplify and find the excluded values of (x^2 + 5x + 4) / (x^2 - 16)?

$\frac{x + 1}{x - 4}$
$f \left(x\right) = \frac{N}{D} = \frac{{x}^{2} + 5 x + 4}{{x}^{2} - 16}$
$f \left(x\right) = \frac{x + 1}{x - 4}$, with conditions: x different to $\pm 4$