Question 446591
1. Geometric, common ratio is a.


2. Geometric, common ratio is -1. This series does not converge though, the ratio has to be strictly between -1 and 1 for the series to converge.


3. I presume you mean


*[tex \LARGE \sum_{n=1}^{\infty} (3 + na)] where *[tex \infty] is the infinity symbol and *[tex \sum] is the Greek uppercase letter sigma. If a is a constant, then the series is


*[tex \LARGE (3 + n) + (3 + 2n) + (3 + 3n) + ...], in which the sequence determined is arithmetic with common difference n.