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Three numbers (Posted on 2003-11-17) Difficulty: 3 of 5
If x, y and z are real numbers such that: x + y + z = 5 and xy + yz + zx = 3, what is the largest value that x can have ?

No Solution Yet Submitted by Ravi Raja    
Rating: 3.7500 (4 votes)

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Question Also this way to think about it. | Comment 7 of 21 |
If x = 5, y = -z. This means yz is negative (assuming y and z are real), and since yx = -zx, 3 = something negative. This is a contradiction, so it doesn't work.

I can't find a flaw yet in Charlie's solution; is this just extraneous solutions again?
  Posted by Gamer on 2003-11-17 16:57:38
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