Jawabanmu

2014-02-14T06:36:59+07:00

diketahui barisan geometri
36,12,4,....hitunglah s8
jawab
mencari r
u1=a=3
6
u2=ar^{2-1}
u2=ar^{1}
u2=36r^{1}
12=36r
r= \frac{12}{36}
r= \frac{1}{3}


Sn = a  (1-r^{n} )/ (1-r)
S8 = 36 (1-(( \frac{1}{3})^{8} )/1- \frac{1}{3}
lanjutkan.....



1 3 1
2014-02-14T11:16:56+07:00
S8 = 36 ( 1 - (1/3)^8 ) / 1 - (1/3) =  36 (6560 / 6561) / (2/3) = 53,99
S8 = 36( 1- 0,00006561)/ (2/3) = 36(0,99993439)/0,7 = 36 x 3/2 = 18 x 3 = 54