Chapter 9 - Conic Sections, Sequences, and Series - 9.4 Geometric Sequences - 9.4 Exercises - Page 736: 7

Geometric with ratio $r=2$

$ -6, -12, -24, -48, -96, -192, ... $ $\frac{a_2}{a_1}=\frac{-12}{-6}=2=r$ $ra_2=-24=a_3$ $ra_3=2\times(-24)=-48=a_4$ $ra_4=2\times(-48)=-96=a_5$ and so on. The sequence is geometric with common ratio $r=2$.