jumlah 10 suku pertama dari barisan bilangan 1/4, 1/2, 1, 2, 4, ... adalah...

a= 1/4
r = u2/u1 = 1/2 / 1/4 = 2
n = 10
sn = a (r^n-1)/(r-1)
= 1/4 (2^10-1)/(2-1)
= 1/4 (1024-1)
= 1/4 (1023)
=255,75

*geometri

¼ , ½...
a = ¼
r = ½ ÷ ¼
r = 2

[tex]s10 = \frac{a( {r}^{10} - 1)}{r - 1} \\ s10 = \frac{ \frac{1}{4} ( {2}^{10} - 1) }{2 - 1} \\ s10 = \frac{1024 - 1}{4} \\ s10 = \frac{1023}{4} \\ s10 = 255 \frac{3}{4} [/tex]