Find an explicit rule for the nth term of the arithmetic sequence.
-$$a _ { 18 } = - 47 , a _ { 19 } = 8$$
A) $a _ { n } = - 982 - 55 ( n - 1 )$
B) $a _ { n } = - 982 - 55 ( n + 1 )$
C) $a _ { n } = - 982 + 55 ( n + 1 )$
D) $a _ { n } = - 982 + 55 ( n - 1 )$

Question

Quizplus · Accepted Answer

The common difference is $8 - (-47) = 55$. Using the formula $a_n = a_1 + (n-1)d$, we find $a_1$ by solving $-47 = a_1 + 17 \times 55$, giving $a_1 = -982$. Thus, the rule is $a_n = -982 + 55(n-1)$.

Find an Explicit Rule for the Nth Term of the Arithmetic