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Suma de la serie ((n+(-1)^n)/(n(n-1)))x^n



=

Solución

Ha introducido [src]
  oo              
____              
\   `             
 \            n   
  \   n + (-1)   n
  /   ---------*x 
 /    n*(n - 1)   
/___,             
n = 2             
$$\sum_{n=2}^{\infty} x^{n} \frac{\left(-1\right)^{n} + n}{n \left(n - 1\right)}$$
Sum(((n + (-1)^n)/((n*(n - 1))))*x^n, (n, 2, oo))
Respuesta [src]
// 2 /  2   (2 + 2*x)*log(1 + x)\              \                                            
||x *|- - + --------------------|              |                                            
||   |  x             2         |              |   //-x*log(1 - x)  for And(x >= -1, x < 1)\
||   \               x          /              |   ||                                      |
||-------------------------------  for |x| <= 1|   ||  oo                                  |
||               2                             |   ||____                                  |
||                                             |   ||\   `                                 |
||          oo                                 |   || \        n                           |
|<        ____                                 | + |<  \    n*x                            |
||        \   `                                |   ||   )  ------          otherwise       |
||         \        n  n                       |   ||  /    2                              |
||          \   (-1) *x                        |   || /    n  - n                          |
||           )  --------            otherwise  |   ||/___,                                 |
||          /     2                            |   ||n = 2                                 |
||         /     n  - n                        |   \\                                      /
||        /___,                                |                                            
\\        n = 2                                /                                            
$$\begin{cases} - x \log{\left(1 - x \right)} & \text{for}\: x \geq -1 \wedge x < 1 \\\sum_{n=2}^{\infty} \frac{n x^{n}}{n^{2} - n} & \text{otherwise} \end{cases} + \begin{cases} \frac{x^{2} \left(- \frac{2}{x} + \frac{\left(2 x + 2\right) \log{\left(x + 1 \right)}}{x^{2}}\right)}{2} & \text{for}\: \left|{x}\right| \leq 1 \\\sum_{n=2}^{\infty} \frac{\left(-1\right)^{n} x^{n}}{n^{2} - n} & \text{otherwise} \end{cases}$$
Piecewise((x^2*(-2/x + (2 + 2*x)*log(1 + x)/x^2)/2, |x| <= 1), (Sum((-1)^n*x^n/(n^2 - n), (n, 2, oo)), True)) + Piecewise((-x*log(1 - x), (x >= -1)∧(x < 1)), (Sum(n*x^n/(n^2 - n), (n, 2, oo)), True))

    Ejemplos de hallazgo de la suma de la serie