tolong dibantu ya....

jawab

deret geometri
u2 = 10
u5 = 10/27

u5/u2 = 10/27 /(10)
r³ = 1/27
r = 1/3

U2 = 10
a= 10/r
a= 10 /(1/3)
a= 30

sn =  a (1 - rⁿ) / ( 1- r)
sn = 30 ( 1- 1/3^ⁿ) / ( 1 - 1/3)
Sn = 3/2 (30) ( 1 - 1/3ⁿ)
sn = 45  ( 1- 3⁻ⁿ)
sn = 5. 9 (1 - 3⁻ⁿ)
sn = 5 ( 9 - 3²⁻ⁿ)