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Límite de la función factorial(n)^2*(1+5^n)*factorial(2+2*n)/((1+5*5^n)*factorial(2*n)*factorial(1+n)^2)

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Gráfico:

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Solución

Ha introducido [src]
     /    2 /     n\             \
     |  n! *\1 + 5 /*(2 + 2*n)!  |
 lim |---------------------------|
n->oo|/       n\                2|
     \\1 + 5*5 /*(2*n)!*(1 + n)! /
$$\lim_{n \to \infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right)$$
Limit(((factorial(n)^2*(1 + 5^n))*factorial(2 + 2*n))/((((1 + 5*5^n)*factorial(2*n))*factorial(1 + n)^2)), n, oo, dir='-')
Método de l'Hopital
Tenemos la indeterminación de tipo
oo/oo,

tal que el límite para el numerador es
$$\lim_{n \to \infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 \left(n + 1\right)\right)!}{\left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \infty$$
y el límite para el denominador es
$$\lim_{n \to \infty}\left(5 \cdot 5^{n} + 1\right) = \infty$$
Vamos a probar las derivadas del numerador y denominador hasta eliminar la indeterminación.
$$\lim_{n \to \infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right)$$
=
Introducimos una pequeña modificación de la función bajo el signo del límite
$$\lim_{n \to \infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 \left(n + 1\right)\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{\frac{d}{d n} \frac{\left(5^{n} + 1\right) n!^{2} \left(2 \left(n + 1\right)\right)!}{\left(2 n\right)! \left(n + 1\right)!^{2}}}{\frac{d}{d n} \left(5 \cdot 5^{n} + 1\right)}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{5^{- n} \left(\frac{5^{n} \log{\left(5 \right)} n!^{2} \left(2 n + 2\right)!}{\left(2 n\right)! \left(n + 1\right)!^{2}} + \frac{2 \cdot 5^{n} n!^{2} \Gamma\left(2 n + 3\right) \operatorname{polygamma}{\left(0,2 n + 3 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} - \frac{2 \cdot 5^{n} n!^{2} \left(2 n + 2\right)! \Gamma\left(n + 2\right) \operatorname{polygamma}{\left(0,n + 2 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{3}} - \frac{2 \cdot 5^{n} n!^{2} \left(2 n + 2\right)! \Gamma\left(2 n + 1\right) \operatorname{polygamma}{\left(0,2 n + 1 \right)}}{\left(2 n\right)!^{2} \left(n + 1\right)!^{2}} + \frac{2 \cdot 5^{n} n! \left(2 n + 2\right)! \Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} + \frac{2 n!^{2} \Gamma\left(2 n + 3\right) \operatorname{polygamma}{\left(0,2 n + 3 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} - \frac{2 n!^{2} \left(2 n + 2\right)! \Gamma\left(n + 2\right) \operatorname{polygamma}{\left(0,n + 2 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{3}} - \frac{2 n!^{2} \left(2 n + 2\right)! \Gamma\left(2 n + 1\right) \operatorname{polygamma}{\left(0,2 n + 1 \right)}}{\left(2 n\right)!^{2} \left(n + 1\right)!^{2}} + \frac{2 n! \left(2 n + 2\right)! \Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}}\right)}{5 \log{\left(5 \right)}}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{5^{- n} \left(\frac{5^{n} \log{\left(5 \right)} n!^{2} \left(2 n + 2\right)!}{\left(2 n\right)! \left(n + 1\right)!^{2}} + \frac{2 \cdot 5^{n} n!^{2} \Gamma\left(2 n + 3\right) \operatorname{polygamma}{\left(0,2 n + 3 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} - \frac{2 \cdot 5^{n} n!^{2} \left(2 n + 2\right)! \Gamma\left(n + 2\right) \operatorname{polygamma}{\left(0,n + 2 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{3}} - \frac{2 \cdot 5^{n} n!^{2} \left(2 n + 2\right)! \Gamma\left(2 n + 1\right) \operatorname{polygamma}{\left(0,2 n + 1 \right)}}{\left(2 n\right)!^{2} \left(n + 1\right)!^{2}} + \frac{2 \cdot 5^{n} n! \left(2 n + 2\right)! \Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} + \frac{2 n!^{2} \Gamma\left(2 n + 3\right) \operatorname{polygamma}{\left(0,2 n + 3 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}} - \frac{2 n!^{2} \left(2 n + 2\right)! \Gamma\left(n + 2\right) \operatorname{polygamma}{\left(0,n + 2 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{3}} - \frac{2 n!^{2} \left(2 n + 2\right)! \Gamma\left(2 n + 1\right) \operatorname{polygamma}{\left(0,2 n + 1 \right)}}{\left(2 n\right)!^{2} \left(n + 1\right)!^{2}} + \frac{2 n! \left(2 n + 2\right)! \Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}{\left(2 n\right)! \left(n + 1\right)!^{2}}\right)}{5 \log{\left(5 \right)}}\right)$$
=
$$\frac{4}{5}$$
Como puedes ver, hemos aplicado el método de l'Hopital (utilizando la derivada del numerador y denominador) 1 vez (veces)
Gráfica
Respuesta rápida [src]
4/5
$$\frac{4}{5}$$
Otros límites con n→0, -oo, +oo, 1
$$\lim_{n \to \infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \frac{4}{5}$$
$$\lim_{n \to 0^-}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \frac{2}{3}$$
Más detalles con n→0 a la izquierda
$$\lim_{n \to 0^+}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \frac{2}{3}$$
Más detalles con n→0 a la derecha
$$\lim_{n \to 1^-}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \frac{9}{13}$$
Más detalles con n→1 a la izquierda
$$\lim_{n \to 1^+}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = \frac{9}{13}$$
Más detalles con n→1 a la derecha
$$\lim_{n \to -\infty}\left(\frac{\left(5^{n} + 1\right) n!^{2} \left(2 n + 2\right)!}{\left(5 \cdot 5^{n} + 1\right) \left(2 n\right)! \left(n + 1\right)!^{2}}\right) = 1$$
Más detalles con n→-oo