Tentukan jumlah 8 suku pertama deret 6 + 12 + 24 + 48 + ...
Pembahasan:
a = 6, r = 12 : 6 = 2
Sₙ = a(1 – rⁿ)
1 – r
= 6(1 – 2⁸)
1 – 2
= 6(1 – 256)
–1
= 6(–255)
–1
= –1.530
–1
= 1.530