Determine a soma dos termos da P.G. (1,3,9 ...,729 )
An = 729
a₁ = 1
q = a₂ / a₁
q = 3/1
q = 3
n = ?
An = a₁ * qⁿ⁻¹
729 = 1 * 3ⁿ⁻¹
3ⁿ⁻¹ = 729 / 1
3ⁿ⁻¹ = 729
3ⁿ⁻¹ = 3⁶
n - 1 = 6
n = 1 + 6
n = 7
Sn = a₁ * (qⁿ - 1) / q - 1
S₇ = 1 * (3⁷ - 1) / 3 - 1
S₇ = 2187 - 1 / 2
S₇ = 2186 / 2
S₇ = 1 093
