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Sum of series n^2*x^(n-1)



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The solution

You have entered [src]
  oo           
 ___           
 \  `          
  \    2  n - 1
  /   n *x     
 /__,          
n = 1          
$$\sum_{n=1}^{\infty} n^{2} x^{n - 1}$$
Sum(n^2*x^(n - 1), (n, 1, oo))
The answer [src]
/x*(-1 - x)              
|----------   for |x| < 1
|        3               
|(-1 + x)                
|                        
|  oo                    
< ___                    
| \  `                   
|  \    2  n             
|  /   n *x    otherwise 
| /__,                   
|n = 1                   
\                        
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            x            
$$\frac{\begin{cases} \frac{x \left(- x - 1\right)}{\left(x - 1\right)^{3}} & \text{for}\: \left|{x}\right| < 1 \\\sum_{n=1}^{\infty} n^{2} x^{n} & \text{otherwise} \end{cases}}{x}$$
Piecewise((x*(-1 - x)/(-1 + x)^3, |x| < 1), (Sum(n^2*x^n, (n, 1, oo)), True))/x

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