‎"EULER, LEONHARD. - THE FUNDAMENTAL THEOREM OF ALGEBRA.‎
‎Sur le Point de Rebroussement de la seconde Espece de mr. le Marquis de l'Hopital. (On the nispidal points of the second kind of Mons. le Marquis de l'Hopital). (+) Recherches sur les Racines Imaginaires des Equations. (Research on imaginary roots o...‎

‎(Berlin, Haude et Spener, 1770). 4to. No wrappers, as issued in ""Mémoires de l'Academie Royale des Sciences et Belles-Lettres"", Tome V, pp. 203-221, 1 plate and pp. 222-288, 1 engraved plate.‎

Reference : 41596

‎Both papers first edition. The first paper is Euler's discussion of ""Cramers Paradox"" and it contains his inventions of 2 kinds of curves, ""Cusps of first kind"" or keratoid cusp and ""Cups of second kind"" or ramphoid cusp. - Enestroem E 169.The second paper contains Euler's famous proof of ""The fundamental Theorem of Algebra"". - Enestroem E 170.‎