minta tolong dibantu dengan caraa

suku pertama a = 3/2.
U5 = 24
ar^4 = 24
3/2 r^4 = 24
r^4 = 24 × 2/3
r^4 = 16
r^4 = 2^4
r = 2
Sn = a (r^n - 1) /(r -1)
Sn = 3/2( 2^n -1)/(2-1)
Sn = 3/2 (2^n - 1)
Sn = 3/2 × 2^n - 3/2
Sn = 3.2^-1 × 2^n - 3/2
Sn = 3.2^(n-1) - 3/2.....(c)