Question

Find the radius of convergence and interval of convergence
of the series.
1. Sum of ((-1)^n)(x^n)/((1/n)^3) with n=1 -> infinite
2. Sum of ((-1)^n)(x^n)/(n^2) with n=1 -> infinite
3. Sum of (n^n)(x^n) with n=1 -> infinite
4. Sum of ((2x-1)^n)/(5(1/n)^n) with n=1 -> infinite