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(-1/2)^n

Sum of series (-1/2)^n



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The solution

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  oo       
 ___       
 \  `      
  \       n
  /   -1/2 
 /__,      
n = 0      
$$\sum_{n=0}^{\infty} \left(- \frac{1}{2}\right)^{n}$$
Sum((-1/2)^n, (n, 0, oo))
The radius of convergence of the power series
Given number:
$$\left(- \frac{1}{2}\right)^{n}$$
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
$$a_{n} = 1$$
and
$$x_{0} = \frac{1}{2}$$
,
$$d = 1$$
,
$$c = 0$$
then
False

Let's take the limit
we find
False
The rate of convergence of the power series
The answer [src]
2/3
$$\frac{2}{3}$$
2/3
Numerical answer [src]
0.666666666666666666666666666667
0.666666666666666666666666666667
The graph
Sum of series (-1/2)^n

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