If aₙ = 3 - 4n, then what is a₁ + a₂ + a₃ + … + aₙ equal to? [2 + 3 + 4 + … + n = n(n+1)/2] - CDS Elementary Mathematics 2014 (II)

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If aₙ = 3-4n, then what is a₁ + a₂ + a₃ + … + aₙ equal to? [2 + 3 + 4 + … + n = n(n+1)/2]