4. Pada barisan aritmetika, tentukan suku pertama, beda, dan U27 jika a) U4 = 4 dan U5 = 8 b) U15 = 50 dan U17 = 30 c) U6 = 25 dan U10 = 5 d) U12 = 26 dan U15 =
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Pertanyaan
4. Pada barisan aritmetika, tentukan suku pertama, beda, dan U27 jika
a) U4 = 4 dan U5 = 8
b) U15 = 50 dan U17 = 30
c) U6 = 25 dan U10 = 5
d) U12 = 26 dan U15 = 17
a) U4 = 4 dan U5 = 8
b) U15 = 50 dan U17 = 30
c) U6 = 25 dan U10 = 5
d) U12 = 26 dan U15 = 17
1 Jawaban
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1. Jawaban nurrafi77
a) U4 ------> a + 3b = 4
U5 ------> a + 4b = 8
--------------- -
- b = - 4
b = 4
a + 3b = 4
a + 3( 4 ) = 4
a = 4 - 12
= - 8
U27 = -8 + 26(4)
= 96
b) U15 -------> a + 14b = 50
U17 -------> a + 16b = 30
------------------- -
- 2b = 20
b = - 10
a + 14b = 50
a + 14(-10 ) = 50
a = 50 + 140
= 190
U27 = a + 26 b
= 190 + 26 (-10)
= 190 - 260
= -70
c) U6 ----> a + 5b = 25
U10 ---> a + 9b = 5
--------------- -
- 4b = 20
b = - 5
a + 5b = 25
a + 5(-5) = 25
a = 25 + 25
= 50
U27 = 50 + 26(-5)
= 50 - 130
= - 80
d) U12 -----> a + 11b = 26
U15 -----> a + 14b = 17
------------------ -
- 3b = 9
b = - 3
a + 11b = 26
a + 11(-3) = 26
a = 26 + 33
= 59
U27 = 59 + 26(-3)
= 59 - 78
= - 19