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((x/100)ln(x/100)/(exp(x/100)+1)-(1/2)(x/100)ln(x/100)/(exp(x/100)-1))/(ln(2)/2)

Suma de la serie ((x/100)ln(x/100)/(exp(x/100)+1)-(1/2)(x/100)ln(x/100)/(exp(x/100)-1))/(ln(2)/2)



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Solución

Ha introducido [src]
    oo                                  
_________                               
\        `                              
 \                        / x \         
  \                       |---|         
   \        x     / x \   \100/    / x \
    \      ---*log|---|   -----*log|---|
     \     100    \100/     2      \100/
      \    ------------ - --------------
       \       x               x        
       /      ---             ---       
      /       100             100       
     /       e    + 1        e    - 1   
    /      -----------------------------
   /                  /log(2)\          
  /                   |------|          
 /                    \  2   /          
/________,                              
  x = 1                                 
$$\sum_{x=1}^{\infty} \frac{- \frac{\frac{\frac{1}{100} x}{2} \log{\left(\frac{x}{100} \right)}}{e^{\frac{x}{100}} - 1} + \frac{\frac{x}{100} \log{\left(\frac{x}{100} \right)}}{e^{\frac{x}{100}} + 1}}{\frac{1}{2} \log{\left(2 \right)}}$$
Sum((((x/100)*log(x/100))/(exp(x/100) + 1) - ((x/100)/2)*log(x/100)/(exp(x/100) - 1))/((log(2)/2)), (x, 1, oo))
Radio de convergencia de la serie de potencias
Se da una serie:
$$\frac{- \frac{\frac{\frac{1}{100} x}{2} \log{\left(\frac{x}{100} \right)}}{e^{\frac{x}{100}} - 1} + \frac{\frac{x}{100} \log{\left(\frac{x}{100} \right)}}{e^{\frac{x}{100}} + 1}}{\frac{1}{2} \log{\left(2 \right)}}$$
Es la serie del tipo
$$a_{x} \left(c x - x_{0}\right)^{d x}$$
- serie de potencias.
El radio de convergencia de la serie de potencias puede calcularse por la fórmula:
$$R^{d} = \frac{x_{0} + \lim_{x \to \infty} \left|{\frac{a_{x}}{a_{x + 1}}}\right|}{c}$$
En nuestro caso
$$a_{x} = \frac{2 \left(\frac{x \log{\left(\frac{x}{100} \right)}}{100 \left(e^{\frac{x}{100}} + 1\right)} - \frac{x \log{\left(\frac{x}{100} \right)}}{200 \left(e^{\frac{x}{100}} - 1\right)}\right)}{\log{\left(2 \right)}}$$
y
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
entonces
$$1 = \lim_{x \to \infty} \left|{\frac{\frac{x \log{\left(\frac{x}{100} \right)}}{100 \left(e^{\frac{x}{100}} + 1\right)} - \frac{x \log{\left(\frac{x}{100} \right)}}{200 \left(e^{\frac{x}{100}} - 1\right)}}{\frac{\left(x + 1\right) \log{\left(\frac{x}{100} + \frac{1}{100} \right)}}{100 \left(e^{\frac{x}{100} + \frac{1}{100}} + 1\right)} - \frac{\left(x + 1\right) \log{\left(\frac{x}{100} + \frac{1}{100} \right)}}{200 \left(e^{\frac{x}{100} + \frac{1}{100}} - 1\right)}}}\right|$$
Tomamos como el límite
hallamos
$$R^{0} = e^{\frac{1}{100}}$$
$$R^{0} = 1.01005016708417$$
Velocidad de la convergencia de la serie
Respuesta [src]
   oo                                          
_______                                        
\      `                                       
 \         /          / x \            / x \  \
  \        |     x*log|---|       x*log|---|  |
   \       |          \100/            \100/  |
    \    2*|- --------------- + --------------|
     \     |      /       x \       /      x \|
     /     |      |      ---|       |     ---||
    /      |      |      100|       |     100||
   /       \  200*\-1 + e   /   100*\1 + e   //
  /      --------------------------------------
 /                       log(2)                
/______,                                       
 x = 1                                         
$$\sum_{x=1}^{\infty} \frac{2 \left(\frac{x \log{\left(\frac{x}{100} \right)}}{100 \left(e^{\frac{x}{100}} + 1\right)} - \frac{x \log{\left(\frac{x}{100} \right)}}{200 \left(e^{\frac{x}{100}} - 1\right)}\right)}{\log{\left(2 \right)}}$$
Sum(2*(-x*log(x/100)/(200*(-1 + exp(x/100))) + x*log(x/100)/(100*(1 + exp(x/100))))/log(2), (x, 1, oo))
Respuesta numérica [src]
159.857612566929286643315333683
159.857612566929286643315333683
Gráfico
Suma de la serie ((x/100)ln(x/100)/(exp(x/100)+1)-(1/2)(x/100)ln(x/100)/(exp(x/100)-1))/(ln(2)/2)

    Ejemplos de hallazgo de la suma de la serie