Question

Tentukan hasil dari pemangkatan berikut 3^{4} + 3^{3} + 3^{2} + 3^{1} + 3^{0} + 3^{-{1}} + 3^{-{2}}

Answer 1

Verified answer

3^4 + 3^3 + 3^2 + 3^1 + 3^0 + 3^(-1) + 3^(-2)
= (81 + 27 + 9 + 3 + 1 + 1/3 + 1/9)
= 121 + 3/9 + 1/9
= 121 4/9

atau

a = 81
r = 1/3
n = 7

Dn = (a(1 - r^n))/(1 - r)
D7 = (81(1 - (1/3)^7))/(1 - 1/3)
D7 = (81(1 - 1/2187))/(3/3 - 1/3)
D7 = (81(2187/2187 - 1/2187))/(2/3)
D7 = (81 × 2186/2187)/(2/3)
D7 = (177066/2187) × (3/2)
D7 = 531198/4374
D7 = 121 1944/4374
D7 = 121 4/9