Diketahui pola barisan sebagai berikut.

Materi : Pola barisan dan bilangan

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Soal Nomor 1

10, 30, 50, 70, …

Suku pertama = 10 dan beda = 20

Maka rumus pola : Un = 20n – 10

Hasil / Result :

U5 = 20(5) – 10 = 100 – 10 = 90

U6 = 20(6) – 10 = 120 – 10 = 110

U7 = 20(7) – 10 = 140 – 10 = 130

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Soal Nomor 2

2, 3, 8, 11, 16, …

Pola beda = 1, 5, 3, 5, 5, 5, 7, …

• Uganjil ⇒+ ( 1, 3, 5, … )⇒Ugenap
• Ugenap ⇒+5⇒Uganjil

Hasil / Result :

U6 = U5 + 5 = 21

U7 = U6 + 5 = 26

U8 = U7 + 7 = 33

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Soal Nomor 3

5, 4, 9, 8, 13, 12, 17, …

Pola beda = -1, +5 , -1, +5, -1, +5, -1, …

• Uganjil ⇒-1⇒Ugenap
• Ugenap ⇒+5⇒Uganjil

Hasil / Result :

U8 = U7 – 1 = 16

U9 = U8 + 5 = 21

U10 = U9 – 1 = 20

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Semoga bisa membantu

jawaban :

Penyelesaian

1). 10, 30, 50, 70, … , … , …

Tiga pola selanjutnya

U1 U2 U3 U4

10 30 50 70

+20 +20 +20

U5 = 70 + 20 = 90

U6 = 90 + 20 = 110

U7 = 110 + 20 = 130

Maka 10, 30, 50, 70, 90, 110, 130

2). 2, 3, 8, 11, 16, … , … , …

Tiga pola selanjutnya

U1 U2 U3 U4 U5

2 3 8 11 16

+1 +5 +3 +5

U6 = 16 + 3 = 19

U7 = 19 + 5 = 24

U8 = 24 + 3 = 27

Maka 2, 3, 8, 11, 16, 19, 24, 27

3). 5, 4, 9, 8, 13, 12, 17 , … , … , …

Tiga pola selanjutnya

U1 U2 U3 U4 U5 U6 U7

5 4 9 8 13 12 17

-1 +5 -1 +5 -1 +5

U8 = 17 – 1 = 16

U9 = 16 + 5 = 21

U10 = 21 – 1 = 20

Maka 5, 4, 9, 8, 13, 12, 17, 16, 21, 20