Jawabanmu

2014-05-20T23:08:56+07:00
ar^4  =  1
ar        8
r³ = (1/2)³
r = 1/2
ar = 8
(1/2)a = 8
a = 8/(1/2)
a = 16
2014-05-21T02:42:45+07:00
U2 = a.r^2-1 = a.r = 8
U5 = a.r^5-1 = a.r^4 = 1

a.r^4/a.r = 1/8
r^3 = 1/2^3
r = 1/2

U2 = a.r=8
=a. 1/2 =8
a= 16

Jadi nilai a=16 dan rasio (r) = 1/2