Determine the radius of convergence for ∑n=1∞(−1)nx2nn4n\sum_{n=1}^{\infty} \frac{(-1)^n x^{2n}}{n 4^n}∑n=1∞n4n(−1)nx2n.
R=1R = 1R=1
R=2R = 2R=2
R=4R = 4R=4
R=1/2R = 1/2R=1/2