Tolong bantu jawab pliss

Tolong bantu jawab pliss

barisan 2, 4, 8, 16, 32, …

a = 2 r = 2

$U _{n} = {ar}^{n - 1} \ \ U_{n} =2 times {2}^{n - 1} \ \ U_{n} = {2}^{n}$

Sn = a(r^n -1)

r – 1

Sn = 2((2^n) – 1)

2 – 1

Sn = 2^(n+1) – 2