Solución detallada
Tomamos como el límite
$$\lim_{x \to \infty} \left(\frac{\left(-1\right) x}{\left(- \frac{x}{\log{\left(9 \right)}} + 1\right) \log{\left(9 \right)}}\right)^{x}$$
cambiamos
$$\lim_{x \to \infty} \left(\frac{\left(-1\right) x}{\left(- \frac{x}{\log{\left(9 \right)}} + 1\right) \log{\left(9 \right)}}\right)^{x}$$
=
$$\lim_{x \to \infty} \left(\frac{\left(- \frac{x}{\log{\left(9 \right)}} + 1\right) - 1}{- \frac{x}{\log{\left(9 \right)}} + 1}\right)^{x}$$
=
$$\lim_{x \to \infty} \left(- \frac{1}{- \frac{x}{\log{\left(9 \right)}} + 1} + \frac{- \frac{x}{\log{\left(9 \right)}} + 1}{- \frac{x}{\log{\left(9 \right)}} + 1}\right)^{x}$$
=
$$\lim_{x \to \infty} \left(1 - \frac{1}{- \frac{x}{\log{\left(9 \right)}} + 1}\right)^{x}$$
=
hacemos el cambio
$$u = \frac{- \frac{x}{\log{\left(9 \right)}} + 1}{-1}$$
entonces
$$\lim_{x \to \infty} \left(1 - \frac{1}{- \frac{x}{\log{\left(9 \right)}} + 1}\right)^{x}$$ =
=
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\left(u + 1\right) \log{\left(9 \right)}}$$
=
$$\lim_{u \to \infty}\left(\left(1 + \frac{1}{u}\right)^{u \frac{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}{u}} \left(1 + \frac{1}{u}\right)^{\log{\left(9 \right)}}\right)$$
=
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\log{\left(9 \right)}} \lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}$$
=
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}$$
=
$$\left(\left(\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}\right)\right)^{\frac{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}{u}}$$
El límite
$$\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}$$
hay el segundo límite, es igual a e ~ 2.718281828459045
entonces
$$\left(\left(\lim_{u \to \infty} \left(1 + \frac{1}{u}\right)^{u}\right)\right)^{\frac{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}{u}} = e^{\frac{\left(u + 1\right) \log{\left(9 \right)} - \log{\left(9 \right)}}{u}}$$
Entonces la respuesta definitiva es:
$$\lim_{x \to \infty} \left(\frac{\left(-1\right) x}{\left(- \frac{x}{\log{\left(9 \right)}} + 1\right) \log{\left(9 \right)}}\right)^{x} = 9$$
Método de l'Hopital
En el caso de esta función, no tiene sentido aplicar el Método de l'Hopital, ya que no existe la indeterminación tipo 0/0 or oo/oo