Final answer:
The first sequence is neither arithmetic nor geometric. The second sequence is neither arithmetic nor geometric, but the differences between terms are arithmetic. The third sequence is arithmetic.
Step-by-step explanation:
For the first sequence, 7/8, 7/2, 14, 56, ... the ratios between consecutive terms are not constant. Therefore, this sequence is neither arithmetic nor geometric.
For the second sequence, -1/3, 1/3, 1, 3, 5, ..., the ratio between consecutive terms is not constant. However, the differences between consecutive terms form an arithmetic sequence. Therefore, this sequence is neither arithmetic nor geometric, but the differences between consecutive terms are arithmetic.
For the third sequence, 26, 22, 18, 14, ..., the differences between consecutive terms are constant (-4). Therefore, this sequence is arithmetic.