Determine Whether the Sequence Is Arithmetic $a _ { n } = - 8 \left( \frac { 1 } { 5 } \right) ^ { n }$

Multiple Choice

Determine whether the sequence is arithmetic. If so, find the common difference. (Assume that n begins with 1.) $a _ { n } = - 8 \left( \frac { 1 } { 5 } \right) ^ { n }$

A) -8
B) 5
C) $\frac { 1 } { 5 }$
D) 8
E) not arithmetic