Barisan geometri v3=3 dan u5=27.tentukan rumus suku ke-n barisan tersebut,kemudian hitung jumlah 5 suku pertamanya

U3 = 3
ar² = 3
a = 3/r²

U5 = 27
ar^4 = 27
(3/r²)r^4 = 27
3r² = 27
r² = 9
r = 3

a = 3/(3²) = 1/3

Un = ar^{n - 1}
Un = (1/3).3^{n - 1}
Un = 3^{n - 2}

Sn = a(r^n - 1)/(r - 1)
S5 = 1/3(3^5 - 1)/(3 - 1)
S5 = 121/3