$$f(x)=\sqrt{x^{2}+4x-5}; (x-3)$$
$\frac{\sqrt{\left(x-1\right)\left(x+5\right)}}{x-3}$
$\frac{-5x-1}{\sqrt{\left(x-1\right)\left(x+5\right)}\left(x-3\right)^{2}}$
