4.17.1 Define a Sequence

Warm Up

Recall that:

An arithmetic sequence is a sequence in which each term is the previous term plus a constant.

A geometric sequence is a sequence in which each term is a constant times the previous term.

Use the first 5 terms of each sequence to state if the sequence is arithmetic, geometric, or neither.

1. 30, 40, 50, 60, 70, . . .
2. 80, 40, 20, 10, 5, 2.5, . . .
3. 1, 2, 4, 8, 16, 32, . . .
4. 1, $\frac{1}{2}$, $\frac{1}{4}$, $\frac{1}{8}$, $\frac{1}{16}$, . . .
5. 20, 13, 6, –1, –8, . . .
6. 1, 3, 7, 15, 31, . . .