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  • Sum of series:
  • x^n/sqrt(n+1)
  • (1000^n)/n! (1000^n)/n!
  • 2n 2n
  • (x+3)^n/2^n
  • Identical expressions

  • (x+ three)^n/ two ^n
  • (x plus 3) to the power of n divide by 2 to the power of n
  • (x plus three) to the power of n divide by two to the power of n
  • (x+3)n/2n
  • x+3n/2n
  • x+3^n/2^n
  • (x+3)^n divide by 2^n
  • Similar expressions

  • (x-3)^n/2^n

Sum of series (x+3)^n/2^n



=

The solution

You have entered [src]
  oo          
____          
\   `         
 \           n
  \   (x + 3) 
   )  --------
  /       n   
 /       2    
/___,         
n = 1         
$$\sum_{n=1}^{\infty} \frac{\left(x + 3\right)^{n}}{2^{n}}$$
Sum((x + 3)^n/2^n, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{\left(x + 3\right)^{n}}{2^{n}}$$
It is a series of species
$$a_{n} \left(c x - x_{0}\right)^{d n}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{n \to \infty} \left|{\frac{a_{n}}{a_{n + 1}}}\right|}{c}$$
In this case
$$a_{n} = 2^{- n}$$
and
$$x_{0} = -3$$
,
$$d = 1$$
,
$$c = 1$$
then
$$R = -3 + \lim_{n \to \infty}\left(2^{- n} 2^{n + 1}\right)$$
Let's take the limit
we find
$$R = -1$$
The answer [src]
/      3   x                        
|      - + -                        
|      2   2             |3   x|    
|     -------        for |- + -| < 1
|       1   x            |2   2|    
|     - - - -                       
|       2   2                       
<                                   
|  oo                               
| ___                               
| \  `                              
|  \    -n        n                 
|  /   2  *(3 + x)      otherwise   
| /__,                              
\n = 1                              
$$\begin{cases} \frac{\frac{x}{2} + \frac{3}{2}}{- \frac{x}{2} - \frac{1}{2}} & \text{for}\: \left|{\frac{x}{2} + \frac{3}{2}}\right| < 1 \\\sum_{n=1}^{\infty} 2^{- n} \left(x + 3\right)^{n} & \text{otherwise} \end{cases}$$
Piecewise(((3/2 + x/2)/(-1/2 - x/2), |3/2 + x/2| < 1), (Sum(2^(-n)*(3 + x)^n, (n, 1, oo)), True))

    Examples of finding the sum of a series