kak tolong jawab ya, pakai cara ya kak. yang mana saja

No.2
Dik = U1 = 4 cm
U5 = 324 cm
n = 5
Dit = Sn = ?
Peny = Un = a x r^n-1
324 = 4 x r^4
r^4 = 324/4
r^4 = 81
r = 3

Sn = a ( r^n - 1 )/ r - 1
= 4 ( 243 - 1 )/3-1
= 2 ( 242 )
= 484 cm
[tex]thanks[/tex]