tolong bantu yah kak:)

U4 = 10/9
a x r³ = 10/9

U6 = 10/81
a x r pangkat 5 = 10/81
a x r³ x r² = 10/81
10/9 x r² = 10/81
r² = 1/9
r = 1/3

U4 = 10/9
a x (1/3)³ = 10/9
a = 30

U10
= 30 x (1/3) pangkat 9
= 30 x 1/19683
= 10/6561

#semoga membantu