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Sorry for the absolute rookie question.

I need to find an example of

f(x,y) =/= f(y,x), for all x, y.

Of course f(a,b) = ka+mb*i, k, m real would be an example, but is it possible that another function exists, whose range is entirely real? if no, then why not.

Thnaks for all help and hints

Sean
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1 Answers1

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If $x=y$ and $f(x,x)$ is defined, then $f(x,y)=f(y,x)$.

For $x\ne y$, we can use for example $f(x,y)=x-y$. If we want to exclude the possibility $x=y$, we can use $\frac{1}{x-y}$.

André Nicolas
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  • Okey, And i have yet another question, similar to this. thus, to the moderators, shall I ask a new question, or shall I post it as a comment to this. – Sean Feb 18 '14 at 07:13
  • If you write it as a comment, there is a fair chance that no one will see it. – André Nicolas Feb 18 '14 at 07:15
  • thank you for the heads up : http://math.stackexchange.com/questions/680550/another-question-of-function-of-two-variables – Sean Feb 18 '14 at 07:28