(49/50) Pellian Equations

[Albert Chan]

(12-26-2023 08:38 PM)John Keith Wrote:  If the negative solution was computed and
the positive solution wanted, the former is converted to the latter.

(x² − d*y²) = -1
(x² − d*y²)² = 1

(x² + d*y²)² − d*(2xy)² = 1

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Some number theory book prefer solution (x,y) in the form z = x + y*√d

z * conj(z) = -1
z² * conj(z²) = 1

z² = (x + y*√d)² = (x² + d*y²) + (2xy)*√d