Proving a function is one-to-one/onto

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October 5th 2009, 04:57 PM
Projectt

Proving a function is one-to-one/onto

I have a function:

$f(m,n) = mn$

The domain for this is $Z \times Z$ . The range is $Z$ . How can I prove if it is one-to-one, onto, or both?
October 5th 2009, 05:08 PM
Plato

Quote:

Originally Posted by Projectt

I have a function:
$f(m,n) = mn$
The domain for this is $Z \times Z$ . The range is $Z$ . How can I prove if it is one-to-one, onto, or both?

It is clearly not one-to-one: $f(2,3)=f(3,2)$ .
Is it onto? If $z\in \mathbb{Z}$ then is it possible that $f(?,?)=z$ ?
October 5th 2009, 05:20 PM
Projectt

Ohh, I thought Z was some arbitrary set, not the set of all integers. Thanks.

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