In this section we briefly state two results concerning series
*a*
_{n}
with terms
*a*
_{n}
that are not necessarily
≥ 0
. The first result has to do with
absolute convergence and the second with alternating series.

- A series
*a*_{n}is said to converge absolutely if |*a*_{n}| converges. It is a theorem that if any series converges absolutely, then it also converges. - A series
*a*_{n}is said to be alternating if the*a*_{n}alternate between being positive and negative. If*a*_{n}is an alternating series such that |*a*_{n+1}|≤|*a*_{n}| for all*n*≥1 and*a*_{n}= 0 , then*a*_{n}converges. This is called the alternating series test.