Rasio dari a. 243, 81, 27, 9,.... b. 4, 2, 1, 1/2,.... c. 2 1/2, 5, 10, 20,....

rumus : Un = ar^n-1
^:pangkat

a.) U2/U1= ar²-¹/ar¹
81/243 = 243×r / 243×1
1/3 = r
r= 1/3

b.) U2/U1= ar²-¹/ar¹
2/4 = 4r/4×1
1/2 = r
r= 1/2

c.) U2/U1= ar²-¹/ar¹
5 / 2½ = 2½ / 2½×r
5 /5/2 = 5/2 / 5/2 × r
5 × 2/5 = 5/2 × 2/5 × r
2 = 10/10 × r
2 = 1 × r
r= 2