Jawabanmu

2014-05-09T16:37:51+07:00
Un = ar^(n-1) 
U5 = ar⁴ = 162 
U2 = ar = -6 

U5 / U2 
= ar⁴/ar = 162/-6 
= r³ = -27 
r = ³√-27 
r = -3 <--

Semoga membantu :)
1 1 1
2014-05-09T17:41:19+07:00
162/-6 = a x r pangkat 4 / a x r
-27      = r³
∛-27   = r
-3         = r