## Algebra 1: Common Core (15th Edition)

a) There is a common ratio, $r = 2$. So, the sequence is geometric. b) There is no common ratio. So, the sequence is not geometric. But the sequence is arithmetic, the formula is $a_n=a_1+3$. c) There is a common ratio, $r = \frac{1}{3}$. So, the sequence is geometric. d) There is no common ratio. So, the sequence is neither geometric nor arithmetic.