Diketahui S3=21 S4=36
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Diketahui S3=21 S4=36
1 Jawaban
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1. Jawaban nurrafi77
S3 = U1 + U2 + U3
21 = a + a + b + a + 2b
21 = 3a + 3b
S4 = S3 + U4
36 = 3a + 3b + a + 3b
36= 4a + 6b
3a + 3b = 21 dikali 4 ------> 12a + 12b = 84
4a + 6b = 36 dikali 3 ------> 12a + 18b = 108
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- 6 b = - 24
b = 4
3a + 3b = 21
3a + 3(4) = 21
3a = 21 - 12
a = 9/3
= 3
suku pertama = a = 3
beda = b = 4