gimana nih caranya tolong dibantu

U8 ,= 1/8, dan U5 = 1
U8 = ar^7, U5 = ar^4
ar^7 = 1/8
(ar^4).r^3 = 1/8
(1).r^3 = 1/8
r^3 = (1/2)^3
r = 1/2
dari ar^4 = 1, maka
a (1/2)^4 = 1
(1/16)a = 1
a = 16
U10 = ar^9
= 16.(1/2)^9
= (2^4).2^-9
= 2^-5
= 1/2^5
= 1/32