Determine the interval of convergence for ∑n=1∞xnn\sum_{n=1}^{\infty} \frac{x^n}{n}∑n=1∞nxn
(−1,1)(-1, 1)(−1,1)
[−1,1)[-1, 1)[−1,1)
(−1,1](-1, 1](−1,1]
[−1,1][-1, 1][−1,1]