Cantor's Theorem (real analysis)

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KevinL
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Google has my particular homework online. I am doing 1.5.6, 1.5.7, 1.5.8

On 1.5.6 a), I created a function f(x) such that {a} if x = a, {b} if x = b, {c} if x=c. This is 1-1 since each element of A gets mapped to something different. Its obviously not onto.

Skipping down to 1.5.7, I need to create the set B for this function. For any a, it can't be an element of f(a). Does this mean B = the empty set?

If so, I think I can tackle the rest...
 
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If you want help, then I suggest you post your question here. We're not going to do an in depth google search to find your homework.
 
In this case B is going to be the empty set