Question

Suatu barisan geometri diketahui u4 = 16 u7=128, maka s8 adalah...

Answer 1

U4=a.r³=16
u7=a.r^6=128
u7:u4= a.r^6:a.r^3
8=r^3
2=r
a.2^3=16
a=2
s8=a(r^8-1)/r-1
s8= 2(256-1)/2-1
s8=2(255)
s8= 510