The first and ninth terms of an arithmetic sequence are 2/3 and- 4/5, respectively. What is the fifth term?
We can find the common difference, d, as
(2/3) + d (8) = -4/5
d(8) = -4/5 - 2/3
8d = - (12 + 10) / 15 = -22/15
d = -22/ (15 * 8) = -22/120 = -11/60
So....the 5th term is
2/3 - (11/60 ) (4) =
2/3 - 44/60 =
2/3 - 11/15 =
10/15 -11/15 =
-1/15
