Choose the one alternative that best completes the statement or answers the question.
The nth term of a sequence is given. Write the first four terms of the sequence.
-$$a ^ { n } = ( - 1 ) ^ { n + 1 } 3 ^ { n }$$
A) $3 , - 6,9 , - 12$
B) $- 3,6 , - 9,12$
C) $- 3,9 , - 27,81$
D) $3 , - 9,27 , - 81$

Question

Quizplus · Accepted Answer

The nth term of the sequence is given by $a^n = (-1)^{n+1} 3^n$. To find the first four terms, substitute n = 1, 2, 3, and 4 into the formula. For n=1, $a^1 = (-1)^2 3^1 = 3$; for n=2, $a^2 = (-1)^3 3^2 = -9$; for n=3, $a^3 = (-1)^4 3^3 = 27$; for n=4, $a^4 = (-1)^5 3^4 = -81$. Thus, the first four terms are 3, -9, 27, -81.

Choose the One Alternative That Best Completes the Statement or Answers