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Sum of series f(x)



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The solution

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  oo     
 __      
 \ `     
  )   f*x
 /_,     
x = 1    
x=1fx\sum_{x=1}^{\infty} f x
Sum(f*x, (x, 1, oo))
The radius of convergence of the power series
Given number:
fxf x
It is a series of species
ax(cxx0)dxa_{x} \left(c x - x_{0}\right)^{d x}
- power series.
The radius of convergence of a power series can be calculated by the formula:
Rd=x0+limxaxax+1cR^{d} = \frac{x_{0} + \lim_{x \to \infty} \left|{\frac{a_{x}}{a_{x + 1}}}\right|}{c}
In this case
ax=fxa_{x} = f x
and
x0=0x_{0} = 0
,
d=0d = 0
,
c=1c = 1
then
1=limx(xx+1)1 = \lim_{x \to \infty}\left(\frac{x}{x + 1}\right)
Let's take the limit
we find
True

False
The answer [src]
oo*f
f\infty f
oo*f

    Examples of finding the sum of a series