Disputatio:Numerus realis

Sententia extracta ex Disputatio:Infinitas#Real Number

The Latin for "real" in the Mathematical sense is indeed realis. Descartes, Geometria III p. 76 (note that Descartes used a different equal sign, that looked rather like a backwards ∝, but I don't know of a unicode sign that will suffice for that).

Quemadmodum , tametsi tres imaginari possimus in hac , x³—6xx+13x—10 = 0 ; tamen una tantùm est realis; nepe 2; & quod ad reliquas duas attinet , quamvis illæ augeantur , diminuantur, aut multiplicentur, sicut jam exposui ; tamen non nisi imaginariæ fieri possunt.

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