Jawabanmu

2014-05-07T08:39:14+07:00
ar^5  = 2048
ar          8
r^4 = 256 = 4^4 didapat r = 4
ar = 8
4a = 8
a = 2
S5 = 2(4^5 - 1)
             4 - 1
     = 2(1023)
             3
     = 2046/3 = 682