SOLUTION: What is the explicit formula for the geometric series -1, -1/3, -1/9, -1/27,... The answer key states the common ration is -1/3. This doesn't make sense to me. My answer was 1/3

Algebra ->  Sequences-and-series -> SOLUTION: What is the explicit formula for the geometric series -1, -1/3, -1/9, -1/27,... The answer key states the common ration is -1/3. This doesn't make sense to me. My answer was 1/3      Log On


   

Question 1202818: What is the explicit formula for the geometric series -1, -1/3, -1/9, -1/27,...
The answer key states the common ration is -1/3. This doesn't make sense to me. My answer was 1/3.
Answer by ikleyn(52802) About Me  (Show Source):
You can put this solution on YOUR website!
.

The common ratio is 1/3: you are right.


The explicit formula for the n-th term is

    a%5Bn%5D = -%281%2F3%29%5E%28n-1%29,  n = 1, 2, 3, . . .

Solved, with explanations.