Write a Formula for the General Term (The Nth Term) $$\mathbf { a } _ { \mathbf { n } }$$

Multiple Choice

Write a formula for the general term (the nth term) of the arithmetic sequence. Then use the formula for $$\mathbf { a } _ { \mathbf { n } }$$ to find $$a _ { 20 }$$ , the 20th term of the sequence.
- $- 3,3,9,15,21 , \ldots$

A) $a _ { n } = 6 n - 9 ; a _ { 20 } = 111$
B) $a _ { n } = 6 n - 3 ; a _ { 20 } = 117$
C) $a _ { n } = 9 n - 3 ; a _ { 20 } = 177$
D) $a _ { n } = 9 n - 6 ; a _ { 20 } = 174$