Tenemos la indeterminación de tipo
0/0,
tal que el límite para el numerador es
$$\lim_{x \to 0^+}\left(- \operatorname{asin}{\left(x^{3} \right)} + 3 \operatorname{asin}{\left(x^{9} \right)}\right) = 0$$
y el límite para el denominador es
$$\lim_{x \to 0^+}\left(\frac{x \log{\left(2 x^{2} + 1 \right)}}{2}\right) = 0$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{x \to 0^+}\left(\frac{- \operatorname{asin}{\left(x^{3} \right)} + 3 \operatorname{asin}{\left(x^{9} \right)}}{x \log{\left(\sqrt{2 x^{2} + 1} \right)}}\right)$$
=
Introducimos una pequeña modificación de la función bajo el signo del límite
$$\lim_{x \to 0^+}\left(\frac{- \operatorname{asin}{\left(x^{3} \right)} + 3 \operatorname{asin}{\left(x^{9} \right)}}{x \log{\left(\sqrt{2 x^{2} + 1} \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(- \operatorname{asin}{\left(x^{3} \right)} + 3 \operatorname{asin}{\left(x^{9} \right)}\right)}{\frac{d}{d x} \frac{x \log{\left(2 x^{2} + 1 \right)}}{2}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{27 x^{8}}{\sqrt{1 - x^{18}}} - \frac{3 x^{2}}{\sqrt{1 - x^{6}}}}{\frac{2 x^{2}}{2 x^{2} + 1} + \frac{\log{\left(2 x^{2} + 1 \right)}}{2}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(\frac{27 x^{8}}{\sqrt{1 - x^{18}}} - \frac{3 x^{2}}{\sqrt{1 - x^{6}}}\right)}{\frac{d}{d x} \left(\frac{2 x^{2}}{2 x^{2} + 1} + \frac{\log{\left(2 x^{2} + 1 \right)}}{2}\right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{243 x^{25}}{- x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} - \frac{9 x^{7}}{- x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} + \frac{216 x^{7}}{\sqrt{1 - x^{18}}} - \frac{6 x}{\sqrt{1 - x^{6}}}}{- \frac{8 x^{3}}{4 x^{4} + 4 x^{2} + 1} + \frac{6 x}{2 x^{2} + 1}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(\frac{243 x^{25}}{- x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} - \frac{9 x^{7}}{- x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} + \frac{216 x^{7}}{\sqrt{1 - x^{18}}} - \frac{6 x}{\sqrt{1 - x^{6}}}\right)}{\frac{d}{d x} \left(- \frac{8 x^{3}}{4 x^{4} + 4 x^{2} + 1} + \frac{6 x}{2 x^{2} + 1}\right)}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- \frac{2187 x^{60}}{- x^{54} \sqrt{1 - x^{18}} + 3 x^{36} \sqrt{1 - x^{18}} - 3 x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{4374 x^{42} \sqrt{1 - x^{18}}}{- x^{54} + 3 x^{36} - 3 x^{18} + 1} + \frac{2187 x^{42}}{- x^{54} \sqrt{1 - x^{18}} + 3 x^{36} \sqrt{1 - x^{18}} - 3 x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{8019 x^{24}}{- x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{27 x^{18}}{- x^{18} \sqrt{1 - x^{6}} + 3 x^{12} \sqrt{1 - x^{6}} - 3 x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} - \frac{54 x^{12} \sqrt{1 - x^{6}}}{- x^{18} + 3 x^{12} - 3 x^{6} + 1} - \frac{27 x^{12}}{- x^{18} \sqrt{1 - x^{6}} + 3 x^{12} \sqrt{1 - x^{6}} - 3 x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} - \frac{81 x^{6}}{- x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} + \frac{1512 x^{6}}{\sqrt{1 - x^{18}}} - \frac{6}{\sqrt{1 - x^{6}}}}{\frac{128 x^{6}}{16 x^{8} + 32 x^{6} + 24 x^{4} + 8 x^{2} + 1} + \frac{64 x^{4}}{16 x^{8} + 32 x^{6} + 24 x^{4} + 8 x^{2} + 1} - \frac{48 x^{2}}{4 x^{4} + 4 x^{2} + 1} + \frac{6}{2 x^{2} + 1}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- \frac{2187 x^{60}}{- x^{54} \sqrt{1 - x^{18}} + 3 x^{36} \sqrt{1 - x^{18}} - 3 x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{4374 x^{42} \sqrt{1 - x^{18}}}{- x^{54} + 3 x^{36} - 3 x^{18} + 1} + \frac{2187 x^{42}}{- x^{54} \sqrt{1 - x^{18}} + 3 x^{36} \sqrt{1 - x^{18}} - 3 x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{8019 x^{24}}{- x^{18} \sqrt{1 - x^{18}} + \sqrt{1 - x^{18}}} + \frac{27 x^{18}}{- x^{18} \sqrt{1 - x^{6}} + 3 x^{12} \sqrt{1 - x^{6}} - 3 x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} - \frac{54 x^{12} \sqrt{1 - x^{6}}}{- x^{18} + 3 x^{12} - 3 x^{6} + 1} - \frac{27 x^{12}}{- x^{18} \sqrt{1 - x^{6}} + 3 x^{12} \sqrt{1 - x^{6}} - 3 x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} - \frac{81 x^{6}}{- x^{6} \sqrt{1 - x^{6}} + \sqrt{1 - x^{6}}} + \frac{1512 x^{6}}{\sqrt{1 - x^{18}}} - \frac{6}{\sqrt{1 - x^{6}}}}{\frac{128 x^{6}}{16 x^{8} + 32 x^{6} + 24 x^{4} + 8 x^{2} + 1} + \frac{64 x^{4}}{16 x^{8} + 32 x^{6} + 24 x^{4} + 8 x^{2} + 1} - \frac{48 x^{2}}{4 x^{4} + 4 x^{2} + 1} + \frac{6}{2 x^{2} + 1}}\right)$$
=
$$-1$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 3 vez (veces)