For the power series ∑n=1∞(−1)nxnn\sum_{n=1}^{\infty} \frac{(-1)^n x^n}{n}∑n=1∞n(−1)nxn, find the interval of convergence.
(−1,1)(-1, 1)(−1,1)
(−1,1](-1, 1](−1,1]
[−1,1)[-1, 1)[−1,1)
[−1,1][-1, 1][−1,1]