Jawab:(a.) U₅₁ + U₆₈ = 379(b.) U₁₄₇ - U₆₇ = 240
Penjelasan:Diketahui barisan aritmatika{14, 17, ....}{a, U₂}→ a = 14beda = U₂-a = 17-14 = 3→ b = 3
Rumus Un = a+b(n-1)
Ditanya(a.) U₅₁ + U₆₈= a+b(51-1) + a+b(68-1)= a + 50b + a+67b= 2a + 50b + 67b= 2a + 117b= 2(14) + 117(3)= 28 + 351= 379
Ditanya(b.) U₁₄₇ - U₆₇= a+b(147-1) - (a+b(67-1))= a+146b - (a+66b)= a + 146b - a - 66b= 146b - 66b= 80b= 80(3)= 240
(xcvi)
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Jawab:
(a.) U₅₁ + U₆₈ = 379
(b.) U₁₄₇ - U₆₇ = 240
Penjelasan:
Diketahui barisan aritmatika
{14, 17, ....}
{a, U₂}
→ a = 14
beda = U₂-a = 17-14 = 3
→ b = 3
Rumus Un = a+b(n-1)
Ditanya
(a.) U₅₁ + U₆₈
= a+b(51-1) + a+b(68-1)
= a + 50b + a+67b
= 2a + 50b + 67b
= 2a + 117b
= 2(14) + 117(3)
= 28 + 351
= 379
Ditanya
(b.) U₁₄₇ - U₆₇
= a+b(147-1) - (a+b(67-1))
= a+146b - (a+66b)
= a + 146b - a - 66b
= 146b - 66b
= 80b
= 80(3)
= 240
(xcvi)