The nth term

Question

Write the nth term of the sequence as a function of n.

 

(1/3),(-1/6),(1/12),(-1/24)+......

Answer 1

The ratio of successive terms is -1/2.  For example, (1/12)/(-1/6) = -1/2 between the 2nd and 3rd terms.

 

The initial term is 1/3.

 

The nth term is (1/3)(-1/2)^n-1 for n = 1, 2, 3, ...