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 limitwe find
True
False