Convergence of Complex Series and Limit Calculation

[lom]

$$\frac{(-1)^n}{(n!)^2z^n}\\$$
z is a complex number
$$\frac{1}{R}=\lim_{n->\infty}\sqrt[n]{|c_n|}\\$$
$$\frac{1}{R}=\frac{1}{\sqrt[n]{(n!)^2z^n}}\\$$

what to do next?

 

[Mark44]

What's the question? How is the problem stated? This is information you're supposed to supply when you post a problem.