Question

–81, 108, –144, 192, ...

Which formula can be used to describe the sequence?
A.f(x) = –81(4/3)^x-1
B. f(x) = –81(-3/4)^x-1
C. f(x) = –81(-4/3)^x-1
D. f(x) = –81(3/4)^x-1

Answer 1

Answer: C. f(x) = -81(-4/3)^(x-1)

This is just the short answer for all of you that are working on edge.nuity and don't have the time or need for a long explanation. I just took the unit test and this was correct, I hope this helped someone out there :3

Answer 2

r = 108/-81 = -144/108 =192/-144 = -4/3
This is a geometric sequence with a common ratio (r) = -4/3
The nth term of a geometric sequence is given by tn = ar^(n-1) where a is the 1st term.
Therefore, the formular for the sequence is f(x) = -81(-4/3)^(x-1)
Answer: C [f(x) = -81(-4/3)^(x-1)]