Jawabanmu

2014-06-06T05:33:55+07:00
A = 8

u4 = 108
108 = 8 +3b
100/3= b
S5= 5/2(216 +400/3)
S5= 873,333
2014-06-06T06:10:14+07:00
U5=2n+(n-1)
   =2.5+ (5-1)
   = 10 (4)
   = 40

Sn = n/2 (a + un)
S5=5/2 (8+U5)
s5 = 5/2 (8+40)
 5/2 . 48= 120