On Saturday 10 October 2009 23:36:18 Victor Miller wrote: [me:]

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[mod-2 stuff]

[Richard Guy:]

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(x + 3/2)^2 + (y + 3/2)^2 + (z + 3/2)^2 = -7/4. R.

[Victor:]

Except that -7/4 -3*9/4=-34/4. You want the + sign.

Oh yeah. (And indeed it turns out that x=[sqrt(7)-3]/2, y=z=-3/2, solves the original equation. Just not rationally.) So maybe I'm not an idiot after all. -- g