Find the 8th term of the geometric sequence 7, -21, 63,
The factor seems to be –3 so your sequence would be
Term Number Term Value
1 3
2 –21
3 63
4 –189
5 567
6 –1,701
7 5.103
8 –15,309
.
Sheesh, why am I so clumsy? The first term is 7 of course.
Common ratio = -21/7 = -3
8th term = 7 (-3)^(n - 1) = 7(-3)^(8-1) = 7(-3)^7 = 7 (-2187) = -15309
