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1/(4n^(2)-1)

Sum of series 1/(4n^(2)-1)



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A solução

You have entered [src]
  oo          
____          
\   `         
 \       1    
  \   --------
  /      2    
 /    4*n  - 1
/___,         
n = 0         
$$\sum_{n=0}^{\infty} \frac{1}{4 n^{2} - 1}$$
Sum(1/(4*n^2 - 1), (n, 0, oo))
The radius of convergence of the power series
Given number:
$$\frac{1}{4 n^{2} - 1}$$
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
$$a_{n} = \frac{1}{4 n^{2} - 1}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\left(4 \left(n + 1\right)^{2} - 1\right) \left|{\frac{1}{4 n^{2} - 1}}\right|\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
The answer [src]
-1/2
$$- \frac{1}{2}$$
-1/2
Numerical answer [src]
-0.500000000000000000000000000000
-0.500000000000000000000000000000
Gráfico
Sum of series 1/(4n^(2)-1)

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