Tomamos como el límite
$$\lim_{x \to 7^+}\left(\frac{x^{4} - 16}{- 4 x + \left(x^{2} - 12\right)}\right)$$
cambiamos
$$\lim_{x \to 7^+}\left(\frac{x^{4} - 16}{- 4 x + \left(x^{2} - 12\right)}\right)$$
=
$$\lim_{x \to 7^+}\left(\frac{\left(x - 2\right) \left(x + 2\right) \left(x^{2} + 4\right)}{\left(x - 6\right) \left(x + 2\right)}\right)$$
=
$$\lim_{x \to 7^+}\left(\frac{\left(x - 2\right) \left(x^{2} + 4\right)}{x - 6}\right) = $$
$$\frac{\left(-2 + 7\right) \left(4 + 7^{2}\right)}{-6 + 7} = $$
= 265
Entonces la respuesta definitiva es:
$$\lim_{x \to 7^+}\left(\frac{x^{4} - 16}{- 4 x + \left(x^{2} - 12\right)}\right) = 265$$