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(7n^2+5n-1)^3n+2/4n^2+2

Sum of series (7n^2+5n-1)^3n+2/4n^2+2



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  oo                                
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\   `                               
 \    /                3      2    \
  \   |/   2          \      n     |
  /   |\7*n  + 5*n - 1/ *n + -- + 2|
 /    \                      2     /
/___,                               
n = 1                               
$$\sum_{n=1}^{\infty} \left(\left(\frac{n^{2}}{2} + n \left(\left(7 n^{2} + 5 n\right) - 1\right)^{3}\right) + 2\right)$$
Sum((7*n^2 + 5*n - 1)^3*n + n^2/2 + 2, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\left(\frac{n^{2}}{2} + n \left(\left(7 n^{2} + 5 n\right) - 1\right)^{3}\right) + 2$$
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
$$a_{n} = \frac{n^{2}}{2} + n \left(7 n^{2} + 5 n - 1\right)^{3} + 2$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left|{\frac{n^{2}}{2} + n \left(7 n^{2} + 5 n - 1\right)^{3} + 2}\right|}{\frac{\left(n + 1\right)^{2}}{2} + \left(n + 1\right) \left(5 n + 7 \left(n + 1\right)^{2} + 4\right)^{3} + 2}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
Numerical answer
The series diverges
The graph
Sum of series (7n^2+5n-1)^3n+2/4n^2+2

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