tentukan jumlah delapan suku pertama deret geometri berikut. 8+4+2... dan 1+5+25+....

Deret Geometri.

8 + 4 + 2 + ...
a = U₁ = 8
r = U₂ / U₁ = 4/8 = 1/2
Sn = a(1 - rⁿ) / (1 - r)
S₈ = 8[1 - (1/2)⁸] / (1 - 1/2)
     = 15,9375

1 + 5 + 25 + ...
Sn = a(rⁿ - 1) / (r - 1)
S₈ = 1(5⁸ - 1) / (5 - 1)
     = 97656