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Sum of series x(x+1)



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The solution

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  oo           
 __            
 \ `           
  )   x*(x + 1)
 /_,           
n = 1          
$$\sum_{n=1}^{\infty} x \left(x + 1\right)$$
Sum(x*(x + 1), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$x \left(x + 1\right)$$
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
$$a_{n} = x \left(x + 1\right)$$
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]
oo*x*(1 + x)
$$\infty x \left(x + 1\right)$$
oo*x*(1 + x)

    Examples of finding the sum of a series