8+24+72+........+2187 a. n b.Sn
Matematika
bella640
Pertanyaan
8+24+72+........+2187
a. n
b.Sn
a. n
b.Sn
1 Jawaban
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1. Jawaban NathanaelEnr
8+24+72+...+2187
r = Un2 ÷ Un1
r = 24 ÷ 8
r = 3
Un = ar^n-1
Un = 8 × 3^n-1
Sn = a (1-r^n) ÷ (1-r)
Sn = 8 (1-3^n) ÷ (1-3)
Sn = 8 (1-3^n) ÷ -2