E696 -- De casibus quibus hanc formulam x4 + kxxyy + y4 ad quadratum reducere licet
(On the cases in which the form x4 + kxxyy + y4 is permitted to be reduced to a square)
Euler first notes that if the values 1, 3, 4, 5, 6, 7, etc. are substituted for k, then the formula never gives a square, regardless of the values x and y. He repeats several of his results about Pell's equation.
Originally published in Nova Acta Academiae Scientarum Imperialis Petropolitinae 10, 1797, pp. 27-40
Opera Omnia: Series 1, Volume 4, pp. 235 - 244
- Reprinted in Commentat. arithm. 2, 1849, pp. 183-189 [E696a]
- Original Publication: E696
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