suku ke 10dari barisan bilangan 80,40,20,10
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Jawab:
Suku ke-10 = ⁵/₃₂
Penjelasan:
Diketahui barisan geometri
{80 40 20 10}
(a) (U₂)
--> Suku awal (a) = 80
rasio = U₂ / a = 40 /80
--> Rasio (r) = ½
Ditanya:
suku ke-10 (n) = 10
Uₙ = a·rⁿ⁻¹
U₁₀ = 80·(½)¹⁰⁻¹
U₁₀ = 80·(½)⁹
U₁₀ = 80 ÷ 2⁹
U₁₀ = (40×2) ÷ 2⁹
U₁₀ = 40 ÷ 2⁸
U₁₀ = 2³ × 5 ÷ 2⁸
U₁₀ = 2³⁻³ × 5 ÷ 2⁸⁻³
U₁₀ = 5 ÷ (2⁵)
U₁₀ = ⁵/₃₂
Suku ke-10 = ⁵/₃₂
(xcvi)
U10 = 5/32
Penjelasan dengan langkah-langkah:
80,40,20,10
a = 80
r = 40/80 = 1/2
Un = a × r^(n - 1)
U10 = 80 × (1/2)^(10 - 1)
U10 = 80 × (1/2)^9
U10 = 80 × (2^(-1))^9
U10 = 80 × 2^(-1×9)
U10 = 80 × 2^-9
U10 = 80/2^9
U10 = 80/512
U10 = 5/32
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