Chapter 5.2A, Problem 24A

In each of the following, find the next two terms. Assume each sequence is arithmetic or geometric, and find its common difference or ratio and the $n\text{th}$ term.

a. ${}^{-}10$, ${}^{-}7$, ${}^{-}4$, ${}^{-}1$, 2, 5, $\dots$

b. ${}^{-}2$, ${}^{-}4$, ${}^{-}8$, ${}^{-}16$, ${}^{-}32$, ${}^{-}64$, $\dots$