Respostas

2014-03-15T14:29:04-03:00
N = 100

a₃ = a₁ + 2r = 10 ⇒ a₁ = 10 - 2r

a₉₈ = a₁ + 97r = 90 ⇒ 10 - 2r + 97r = 90 ⇒ 95r = 80 ⇒ r = 80/95 = 16/19

a₁ = 10 - 32/19 = 158/19

a₁₀₀ = a₉₈ + 2r = 90 + 32/19 = 1742/19

S₁₀₀ = (a₁ + a₁₀₀).100/2 = (158/19 + 1742/19).50 = (1900/19).50 = 100.50 = 5000
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