`a_n = (-1)^n` Write the first 5 terms of the sequence. Determine whether the sequence is arithmetic. If so, then find the common difference....

The first five terms are -1, 1, -1, 1, -1. This sequence is not an arithmetic one because the differences between adjacent terms aren't equal. This is a geometric sequence with the common ratio -1.

The first five terms are -1, 1, -1, 1, -1. This sequence is not an arithmetic one because the differences between adjacent terms aren't equal. This is a geometric sequence with the common ratio -1.