For the sequence 1, 7, 25, 79, 241, 727 … simple formula for {an} is ____________.
A. 3n+1 – 2
B. 3n – 2
C. (-3)n + 4
D. n2 – 2
Answer:A
For the sequence 1, 7, 25, 79, 241, 727 … simple formula for {an} is ____________.
A. 3n+1 – 2 B. 3n – 2 C. (-3)n + 4 D. n2 – 2
Explanation: The ratio of consecutive numbers is close to 3. Comparing these terms with the sequence of {3n} which is 3, 9, 27 …. Comparing these terms with the corresponding terms of sequence {3n} and the nth term is 2 less than the corresponding power of 3.