Jumlah 10 suku pertama deret tersebut yakni …
Pembahasan:
Barisan geometri
U₂ = 100
U₆ = 160
S₁₀ = …?
r⁴ = U₆ = 160 = 16 ⇒ r = 2
U₂ 10
U₂ = ar
a = U₂/r = 10/2 = 5
Sₙ = a(rⁿ – 1)
r – 1
S₁₀ = 5(2¹⁰ – 1) = 5 × 1023 = 5115
2 – 1