Find an explicit rule for the nth term of the arithmetic sequence.
-$$- 9 , - 17 , - 25 , - 33 , \ldots$$
A) $a _ { n } = - 9 - ( - 8 ) ( n + 1 )$
B) $a _ { n } = - 9 + ( - 8 ) ( n - 1 )$
C) $a _ { n } = - 9 + ( - 8 ) ( n + 1 )$
D) $a _ { n } = - 9 \times ( - 8 ) ( n - 1 )$

Question

Quizplus · Accepted Answer

The common difference in the sequence is $-8$ (subtracting 8 each time), and the first term is $-9$. The formula for the nth term of an arithmetic sequence is $a_n = a_1 + (n - 1)d$, where $a_1$ is the first term and $d$ is the common difference. Substituting $-9$ for $a_1$ and $-8$ for $d$ gives $a_n = -9 + (-8)(n - 1)$.

Find an Explicit Rule for the Nth Term of the Arithmetic