Which of the following series converge? (i) ∑n=1∞2n(n+1)\sum_{n=1}^{\infty} \frac{2}{n(n+1)}∑n=1∞n(n+1)2; (ii) ∑n=1∞3n\sum_{n=1}^{\infty} \frac{3}{n}∑n=1∞n3; (iii) ∑n=1∞12n\sum_{n=1}^{\infty} \frac{1}{2^n}∑n=1∞2n1
(i) and (ii)
(i) and (iii)
(ii) only
All three