Find 4 different positive integers A,B,C,D for which:
A+B = C*D and
A*B = C+D
How many sets of 4 numbers can you find? Prove that only those sets exist.
If you read the rest of that sentence, gamer states 'it is a contradiction' part of his proof that there must be at least one "1" in the set. Substituting A for 1, he continues with the rest of his answer.
In other words, he's showing us a contradiction; it's not supposed to look 'right'.

Posted by duane
on 20050923 20:25:46 