SOLUTION: Find the nth term, the fifth term, and the eighth term of the geometric sequence.. 64, 16, 4, 1 ...... an= a8=

Algebra ->  Sequences-and-series -> SOLUTION: Find the nth term, the fifth term, and the eighth term of the geometric sequence.. 64, 16, 4, 1 ...... an= a8=      Log On


   



Question 634665: Find the nth term, the fifth term, and the eighth term of the geometric sequence..
64, 16, 4, 1 ......
an=
a8=

Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Find the nth term, the fifth term, and the eighth term of the geometric sequence..
For a geometric sequence, if A is the first term, and R is the ratio
of any two adjacent terms, then the nth term is given by the formula
.
A*R^(n-1)
.
64, 16, 4, 1 ......
R (ratio) is 1/4
A is 64
.
.
So, for:
an= 64(1/4)^(n-1)
.
a8= 64(1/4)^(8-1)
a8= 64(1/4)^7
a8= 4^3/4^7
a8= 1/4^4
a8= 1/256