Which of the following is true for the sequence an=5⋅(−1)na_n = 5 \cdot (-1)^nan=5⋅(−1)n?
It is a geometric sequence with r=1r = 1r=1.
It is a geometric sequence with r=−1r = -1r=−1.
It is not a geometric sequence.
It converges to 0.