tentukan nilai x jika x = 1/3+1/9+1/27+...

Deret geometri
r = 1/3, jadi pasti konvergen ke jumlah
S= a / (1 - r).

S = (1/3)/(1 - 1/3) = (1/3)/(2/3) = 1/2 = 0.5

cara lain, pakek aljabar :
x = 1/3 + 1/9 + 1/27 + 1/81 + ...
x = 1/3 + 1/3(1/3 + 1/9 + 1/27 + ....)
x = 1/3 + 1/3 x
x - 1/3 x = 1/3
(2/3)x = 1/3
x = (1/3) / (2/3)
x =  1/2