Tentukan unsur aritmatika a=5, u5=11, s15=...
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fitri1589
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Tentukan unsur aritmatika a=5, u5=11, s15=...
1 Jawaban
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1. Jawaban Anonyme
U5 = a + 4b = 11
5 + 4b = 11
b = 3/2
S15 = (n/2)(2a + (n-1)b)
S15 = (15/2)(10 + 14(3/2))
S15 = (15/2)(10 + 21)
S15 = 232,5