Chapter 9 - Conic Sections, Sequences, and Series - 9.4 Geometric Sequences - 9.4 Exercises - Page 736: 8

Geometric with ratio $r=3$

$-7, -21, -63, -189, -567, -1701, . . . $ $\frac{a_2}{a_1}=\frac{-21}{-7}=3=r$ $ra_2=3\times(-21)=-63=a_3$ $ra_3=3\times(-63)=-189=a_4$ $ra_4=2\times(-189)=-567=a_5$ and so on. The sequence is geometric with common ratio $r=3$.