mohon bantuannya tentang soal Geometri, jika U3 = 12 U8=384 maka U10=....?

r = akar pangkat 8-3 dari(384 ÷ 12)
r = akar pangkat lima dari 32
r = 2
a = (12÷2)÷2
a = 3

Un = a × r^n-1
U10 = 3 × 2^9
U10 = 3 × 512
U10 = 1.536

U8 = U1 × r^7 = 384
U3 = U1 × r^2 = 12
-------------------------- :
r^5 = 32
r^5 = 2^5
r = 2


U3 = U1 × r^2
12 = U1 × 2^2
12 = U1 × 4
12/4 = U1
3 = U1


Un = U1 × r^n-1
U10 = 3 × 2^10-1
= 3 × 2^9
= 3 × 512
= 1.536