Pell's equation Bézout's theorem This result was discovered first by Newton in 1665.
From the wikipedia article: "The name of this equation arose from Even though MacLaurin (1720) and Leonhard Euler's mistakenly attributing its study to John Pell. Euler was aware of the work of Lord Brounckergave proofs, the first European mathematician theorem is usually attributted to find a general solution Etienne Bézout who much later (1776) gave an incorrect proof of the equation, but apparently confused Brouncker with Pellresult.This equation was first studied extensively in ancient India, starting with Brahmagupta.."
