find the numbers of this geometric sequence: 8, __ , __, __, 648

Answer 1

8, 8r, 8r^2, 8r^3, 8r^4
but 8r^4 = 648
r^4 = 81
r = ± 3

you have either
8, 24, 72, 216, 648
or
8, -24, 72, -216, 648

Answer 2

The common ratio is (648/8)^(1/4) = 3
8*3=24
24*3=72
72*3=216
216*3=648