Talk:Pell's equation

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<quote> It turns out that if (p, q) satisfies Pell's equation, then so does (2pq, 2q^2-1).</quote>

Does it?

n(2q² − 1)² + 1 = 4nq⁴ − 4nq² + n + 1;4p²q² = 4(nq² + 1)q² = 4nq⁴ + 4q²

Which aren't generally equal. (Probably only for n = -1) --User:Xaos

[edit] Indeterminate equations

I removed the words "quadratic indeterminate" from

"Pell's equation is any quadratic indeterminate Diophantine equation of the form x² − ny² = 1."

because the form already says that the equation is quadratic and indeterminate (in the sense of underdetermined). It is claimed that "there are many scholars referring to Pell's equation as an indeterminate equation", but I've seen no evidence for it and I still doubt that it's a standard term; anyway, it clearly is superfluous. -- Jitse Niesen (talk) 07:49, 10 April 2006 (UTC)