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1) 7, 11, 15
suku pertama a = 7 dan beda b = 11-7 = 15-11 = 4
Un = a + (n-1)b
U15 = a + 14b.
U15 = 7 + 14.4
U15 = 7 + 56
U15 = 63
2) 4, 8, 12
suku pertama a = 4 dan beda b = 8-4 = 12-8 = 4
U12 = a + 11b
U12 = 4 + 11.4
U12 = 4 +44
U12 = 48
3) 1, 3, 5,
suku pertama a = 1, dan beda b = 3-1 = 5-3 = 2
U20 = a + 19b
U20 = 1 + 19.2
U20 = 1 + 38
U20 = 39
4) 4, 6, 10, 16
penambahan = 2 , 4, 6, 8, 10,12, 14, 16, 18, 20, 22, 24
penambahan 2n
suku pertama= 4
U20 = a + (19.2)
U20 = 4 + 38
U20 = 44