Barisan geometri u3=6 u5=48 berapa u7?

Un=ar^n-1

U3= 6
ar^3-1 = 6
ar² = 6 .... persamaan 1)

U5=48
ar^n-1 = 48
ar^4 = 48 .... persamaan 2)

kedua persamaan dieliminasi
ar²/ar^4 = 6/48
1/r² = 1/8
r² = 8
r = 2√2
mencari a
ar² = 6
a = 6/r² = 6/(2√2)² = 6/8

maka U7=?
U7 = ar^7-1
= ar^6
= 6/8 (2√2)^6
= 6/8 . 512
= 384