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- May 8th 2010, 03:59 PMslipz418Set Theory help..
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Thank you.. - May 8th 2010, 04:14 PMPlato
**This is not a homework service**

slipz418, you have posted a set of three problems.

They are nice problems.

What do you expect from us?

Remember that this is not a homework service - May 8th 2010, 04:15 PMgmatt
I'll try to give you some guidance,

the definition of one-to-one is:

$\displaystyle \forall x,y \in \mathbb{R} f(x)=f(y) \implies x = y $

and onto:

$\displaystyle \forall y \in \mathbb{R} \exists x \in \mathbb{R} f(x) = y$.

Also to prove that something is not one to one you need to find $\displaystyle x,y\in \mathbb{R}$ such that $\displaystyle f(x) = f(y)$ and $\displaystyle x \neq y$.

Hope that helps.