Tomamos como el límite
$$\lim_{x \to 5^+}\left(\frac{9 - x^{2}}{- x + \left(x^{2} - 6\right)}\right)$$
cambiamos
$$\lim_{x \to 5^+}\left(\frac{9 - x^{2}}{- x + \left(x^{2} - 6\right)}\right)$$
=
$$\lim_{x \to 5^+}\left(\frac{\left(-1\right) \left(x - 3\right) \left(x + 3\right)}{\left(x - 3\right) \left(x + 2\right)}\right)$$
=
$$\lim_{x \to 5^+}\left(- \frac{x + 3}{x + 2}\right) = $$
$$- \frac{3 + 5}{2 + 5} = $$
= -8/7
Entonces la respuesta definitiva es:
$$\lim_{x \to 5^+}\left(\frac{9 - x^{2}}{- x + \left(x^{2} - 6\right)}\right) = - \frac{8}{7}$$