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Sum of series 2-x+x^2



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The solution

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  oo              
 ___              
 \  `             
  \   /         2\
  /   \2 - x + x /
 /__,             
n = 1             
$$\sum_{n=1}^{\infty} \left(x^{2} + \left(2 - x\right)\right)$$
Sum(2 - x + x^2, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$x^{2} + \left(2 - x\right)$$
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
$$a_{n} = x^{2} - x + 2$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty} 1$$
Let's take the limit
we find
True

False
The answer [src]
   /     2    \
oo*\2 + x  - x/
$$\infty \left(x^{2} - x + 2\right)$$
oo*(2 + x^2 - x)

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