Tentukan rasio dari barisan geometri (a+2), (a-1), (a-7)

jawab


(a+2) , (a-1), (a-7)

(a-1)² = (a +2)(a - 7)
a² - 2a + 1 = a² -5a - 14
-2a + 1= -5a - 14
-2a + 5a = -14 - 1
3a = - 15
a = -5

r = (a-1)/(a+2)
r = (-5 -1)/(-5+2)
r = -6/-3
r = 2