Dketahui barisan geometri U1 + U2 = 45 DAN U3 + U4 = 20 tentukan rasiaonya ?

U1 + U2 = a + ab = 45
U3 + U4 = abb + abbb = 20

(a + ab = 45) << dikali dengan bb
(a + ab)bb = 45bb
abb + abbb = 45bb

45bb = 20
bb = 20/45 = 4/9
b = akar (4/9)
b = 2/3