Question

Determine a soma dos termos da p.g (1,3,9,...7,29)

Answer 1

Boa noite!

Dados;
A1 = 1
An = 729
Q = a2÷a1 = 3÷1 = 3
N = 7
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Entendo que seja; (1,3,9...729)
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An = a1×q⁽ⁿ⁻¹⁾
729 = 1 × 3⁽ⁿ⁻¹⁾
729/1 = 3⁽ⁿ⁻¹⁾
729 = 3⁽ⁿ⁻¹⁾
3⁶ = 3⁽ⁿ⁻¹⁾
6 = n-1
6+1 = n
n = 7

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Sn = an × q- a1
             q-1

S8 = 729 × 3 - 1
            3-1

S8 =2187-1
            2

S8 = 2186
            2

S8 =1093


Att;Guilherme Lima