Pell's Equation
x^2 - n y^2 = 1
(Pell's equation) which is named after the English mathematician John Pell. It was studied by Brahmagupta in the 7th century, as well as by Fermat in the 17th century.
http://en.wikipedia.org/wiki/Pell%27s_equation
x^2 - n y^2 = 1
(Pell's equation) which is named after the English mathematician John Pell. It was studied by Brahmagupta in the 7th century, as well as by Fermat in the 17th century.
http://en.wikipedia.org/wiki/Pell%27s_equation