For the power series ∑n=1∞(1/2n)xn\sum_{n=1}^{\infty} \binom{1/2}{n} x^n∑n=1∞(n1/2)xn, what is 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)