Jawabanmu

2014-02-16T09:59:48+07:00
Un=6.3-n

U1= 17
U2= 16
U3= 15
U8= 10


Sn = 1/2 n(a+Un)
S8 = 1/2 8 (17 + 18-8)
S8 = 4 x 27
S8 = 108
2014-02-16T10:57:47+07:00
Dik:
Un= 6. 3^1-n
dit:
S8=...?
Jawab:
Un= 6. 3^1-n     
U8= 6. 3-8            U1= 6. 3-1
    = 18-8=10            = 18-1=17
S8= 1/2n(U1 + Un)
    = 1/2.8(17 + 18)
    =4(35)
    =140.
Klo bnar jadiin the best y...