E523 -- De tribus numeris quadratis, quorum tam summa quam summa productorum ex binis sit quadratum

(On three square numbers, of which the sum and the sum of products two apiece will be a square)


Euler wants xx + yy + zz and xxyy + xxzz + yyzz both to be squares.

According to the records, it was presented to the St. Petersburg Academy on September 7, 1780.

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