Tenemos la indeterminación de tipo
0/0,
tal que el límite para el numerador es
$$\lim_{x \to 0^+}\left(\cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}\right) = 0$$
y el límite para el denominador es
$$\lim_{x \to 0^+} \sin^{23}{\left(\pi x \right)} = 0$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{x \to 0^+}\left(\frac{\cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{\sin^{23}{\left(\pi x \right)}}\right)$$
=
Introducimos una pequeña modificación de la función bajo el signo del límite
$$\lim_{x \to 0^+}\left(\frac{\cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{\sin^{23}{\left(\pi x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{\frac{d}{d x} \sin^{23}{\left(\pi x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{7 \pi \left(\tan^{2}{\left(7 \pi x \right)} + 1\right) \cos{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)} + 9 \pi \left(\tan^{2}{\left(9 \pi x \right)} + 1\right) \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} - 7 \pi \sin{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{23 \pi \sin^{22}{\left(\pi x \right)} \cos{\left(\pi x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- 7 \pi \sin{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)} + 7 \pi \cos{\left(7 \pi x \right)} \tan^{2}{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)} + 9 \pi \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan^{2}{\left(9 \pi x \right)} + 9 \pi \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} + 7 \pi \cos{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{23 \pi \sin^{22}{\left(\pi x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- 7 \pi \sin{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)} + 7 \pi \cos{\left(7 \pi x \right)} \tan^{2}{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)} + 9 \pi \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} \tan^{2}{\left(9 \pi x \right)} + 9 \pi \cos{\left(7 \pi x \right)} \tan{\left(7 \pi x \right)} + 7 \pi \cos{\left(7 \pi x \right)} \tan{\left(9 \pi x \right)}}{23 \pi \sin^{22}{\left(\pi x \right)}}\right)$$
=
$$\infty$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 1 vez (veces)