Determine a positive integer constant c such that the equation xy² - y²+ x+ y = c has precisely three solutions in positive integers.

(In reply to solutions (spoiler) by Daniel)

Comparing your list to mine, I see 90 and 92 are on my list but not yours (besides the numbers that exceed 100).

 x   y          c
 45  1         90
 6   4         90
 1   89        90
 46  1         92
 2   9         92
 1   91        92

Posted by Charlie on 2006-12-02 14:31:00