Răspuns :
Nr. D-₁₂= ? D-₁₂ ∈ Z
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D-₁₂ ={ +/ -1; +/- 12; +/- 2; +/- 6;+/-.3; +/- 4;}
nr.D-₁₂ = 12
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D-₁₂ ={ +/ -1; +/- 12; +/- 2; +/- 6;+/-.3; +/- 4;}
nr.D-₁₂ = 12