tuliskan jumlah deret geometri 1-3+9-27+81,...S15
Matematika
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Pertanyaan
tuliskan jumlah deret geometri 1-3+9-27+81,...S15
1 Jawaban
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1. Jawaban Anonyme
Deret Geometri
1 - 3 + 9 - 27 + ...
a = 1
r = U2/U1 = -3
Sn = a(1 - r^n)/(1 - r)
S15 = 1(1 - (-3)^15)/(1 - (-3))
S15 = (1/4)(1 + 3^15)