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(-1)^n*pi^(2n)/((2n)!)

Sum of series (-1)^n*pi^(2n)/((2n)!)



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The solution

You have entered [src]
  oo             
____             
\   `            
 \        n   2*n
  \   (-1) *pi   
  /   -----------
 /       (2*n)!  
/___,            
n = 1            
$$\sum_{n=1}^{\infty} \frac{\left(-1\right)^{n} \pi^{2 n}}{\left(2 n\right)!}$$
Sum(((-1)^n*pi^(2*n))/factorial(2*n), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{\left(-1\right)^{n} \pi^{2 n}}{\left(2 n\right)!}$$
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
$$a_{n} = \frac{\left(-1\right)^{n}}{\left(2 n\right)!}$$
and
$$x_{0} = - \pi$$
,
$$d = 2$$
,
$$c = 0$$
then
$$R^{2} = \tilde{\infty} \left(- \pi + \lim_{n \to \infty} \left|{\frac{\left(2 n + 2\right)!}{\left(2 n\right)!}}\right|\right)$$
Let's take the limit
we find
$$R^{2} = \infty$$
$$R = \infty$$
The rate of convergence of the power series
The answer [src]
-2
$$-2$$
-2
Numerical answer [src]
-2.00000000000000000000000000000
-2.00000000000000000000000000000
The graph
Sum of series (-1)^n*pi^(2n)/((2n)!)

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