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Límite de la función x*(1-(1+x)*log(1+2/(1+x)^3)/(x*log(1+2/x^3)))

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Ha introducido [src]
     /  /               /       2    \\\
     |  |    (1 + x)*log|1 + --------|||
     |  |               |           3|||
     |  |               \    (1 + x) /||
 lim |x*|1 - -------------------------||
x->oo|  |               /    2 \      ||
     |  |          x*log|1 + --|      ||
     |  |               |     3|      ||
     \  \               \    x /      //
$$\lim_{x \to \infty}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right)$$
Limit(x*(1 - (1 + x)*log(1 + 2/(1 + x)^3)/(x*log(1 + 2/x^3))), x, oo, dir='-')
Método de l'Hopital
Tenemos la indeterminación de tipo
oo/-oo,

tal que el límite para el numerador es
$$\lim_{x \to \infty} \frac{1}{\log{\left(\frac{x^{3} + 2}{x^{3}} \right)}} = \infty$$
y el límite para el denominador es
$$\lim_{x \to \infty} \frac{1}{x \log{\left(\frac{x^{3} + 2}{x^{3}} \right)} - \left(x + 1\right) \log{\left(\frac{\left(x + 1\right)^{3} + 2}{\left(x + 1\right)^{3}} \right)}} = -\infty$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{x \to \infty}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right)$$
=
Introducimos una pequeña modificación de la función bajo el signo del límite
$$\lim_{x \to \infty}\left(\frac{x \log{\left(\frac{x^{3} + 2}{x^{3}} \right)} - \left(x + 1\right) \log{\left(\frac{\left(x + 1\right)^{3} + 2}{\left(x + 1\right)^{3}} \right)}}{\log{\left(\frac{x^{3} + 2}{x^{3}} \right)}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\frac{d}{d x} \frac{1}{\log{\left(\frac{x^{3} + 2}{x^{3}} \right)}}}{\frac{d}{d x} \frac{1}{x \log{\left(\frac{x^{3} + 2}{x^{3}} \right)} - \left(x + 1\right) \log{\left(\frac{\left(x + 1\right)^{3} + 2}{\left(x + 1\right)^{3}} \right)}}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{1}{\left(\frac{x^{4} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2}}{6 \left(x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2} - 2 x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + x^{2} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} - 2 x \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + 2 x \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2}\right)} + \frac{x \log{\left(1 + \frac{2}{x^{3}} \right)}^{2}}{3 \left(x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2} - 2 x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + x^{2} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} - 2 x \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + 2 x \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2}\right)}\right) \left(- \frac{3 x^{7}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{21 x^{6}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{63 x^{5}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{111 x^{4}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{3 x^{4}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{129 x^{3}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{12 x^{3}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{99 x^{2}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{18 x^{2}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{45 x}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{12 x}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \log{\left(1 + \frac{2}{x^{3}} \right)} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} - \frac{9}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{3}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} + \frac{6}{x^{3} + 2}\right)}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{1}{\left(\frac{x^{4} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2}}{6 \left(x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2} - 2 x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + x^{2} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} - 2 x \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + 2 x \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2}\right)} + \frac{x \log{\left(1 + \frac{2}{x^{3}} \right)}^{2}}{3 \left(x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)}^{2} - 2 x^{2} \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + x^{2} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} - 2 x \log{\left(1 + \frac{2}{x^{3}} \right)} \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} + 2 x \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)}^{2}\right)}\right) \left(- \frac{3 x^{7}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{21 x^{6}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{63 x^{5}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} - \frac{111 x^{4}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{3 x^{4}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{129 x^{3}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{12 x^{3}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{99 x^{2}}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{18 x^{2}}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \frac{45 x}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{12 x}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} - \log{\left(1 + \frac{2}{x^{3}} \right)} + \log{\left(\frac{x^{3}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x^{2}}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3 x}{x^{3} + 3 x^{2} + 3 x + 1} + \frac{3}{x^{3} + 3 x^{2} + 3 x + 1} \right)} - \frac{9}{x^{7} + 7 x^{6} + 21 x^{5} + 37 x^{4} + 43 x^{3} + 33 x^{2} + 15 x + 3} + \frac{3}{x^{4} + 4 x^{3} + 6 x^{2} + 6 x + 3} + \frac{6}{x^{3} + 2}\right)}\right)$$
=
$$2$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 1 vez (veces)
Gráfica
Respuesta rápida [src]
2
$$2$$
Otros límites con x→0, -oo, +oo, 1
$$\lim_{x \to \infty}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = 2$$
$$\lim_{x \to 0^-}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = 0$$
Más detalles con x→0 a la izquierda
$$\lim_{x \to 0^+}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = 0$$
Más detalles con x→0 a la derecha
$$\lim_{x \to 1^-}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = \frac{- 2 \log{\left(5 \right)} + \log{\left(3 \right)} + 4 \log{\left(2 \right)}}{\log{\left(3 \right)}}$$
Más detalles con x→1 a la izquierda
$$\lim_{x \to 1^+}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = \frac{- 2 \log{\left(5 \right)} + \log{\left(3 \right)} + 4 \log{\left(2 \right)}}{\log{\left(3 \right)}}$$
Más detalles con x→1 a la derecha
$$\lim_{x \to -\infty}\left(x \left(1 - \frac{\left(x + 1\right) \log{\left(1 + \frac{2}{\left(x + 1\right)^{3}} \right)}}{x \log{\left(1 + \frac{2}{x^{3}} \right)}}\right)\right) = 2$$
Más detalles con x→-oo