Let f(x)=∑n=1∞n2xnf(x) = \sum_{n=1}^{\infty} n^2 x^nf(x)=∑n=1∞n2xn. For what values of xxx does this power series converge?
∣x∣<1|x| < 1∣x∣<1
∣x∣≤1|x| \leq 1∣x∣≤1
x=0x = 0x=0
∣x∣<12|x| < \frac{1}{2}∣x∣<21