Jawabanmu

2014-02-08T18:31:34+07:00
U1 atau a =2 ,r=3 Sn=80 Sn = a.(r^n-1) / (r-1) 80= 2.(3^n -1 / (3-1) 80= 6^n -2 / 2 80 = -3^n