Determine the interval of convergence for ∑n=1∞(x+1)nn3n\sum_{n=1}^{\infty} \frac{(x+1)^n}{n 3^n}∑n=1∞n3n(x+1)n.
(−4,2](-4, 2](−4,2]
[−4,2)[-4, 2)[−4,2)
(−4,2)(-4, 2)(−4,2)
[−4,2][-4, 2][−4,2]