MHB Set Theory Questions (check if right)

[ertagon2]

Could someone please check if these are right?
View attachment 7908

 

[Opalg]

Re: Set Theory Questions (check if irght)

Could someone please check if these are right?

One part of q.1 is wrong. Everything else looks correct.

 

[ertagon2]

Re: Set Theory Questions (check if irght)

One part of q.1 is wrong. Everything else looks correct.

Which one? Looks alright to me.

 

[Opalg]

Re: Set Theory Questions (check if irght)

Which one? Looks alright to me.

Only finitely many rational numbers between 4 and 6 ? (Doh)

 

[ertagon2]

Re: Set Theory Questions (check if irght)

Only finitely many rational numbers between 4 and 6 ? (Doh)

Isn't there a finite number of rational numbers for 4<x<6 ?

 

[Opalg]

Re: Set Theory Questions (check if irght)

Isn't there a finite number of rational numbers for 4<x<6 ?

What about the numbers $4 + \dfrac1n$, for $n=1,\,2,\,3,\,\ldots$ ?

 

[ertagon2]

Re: Set Theory Questions (check if irght)

What about the numbers $4 + \dfrac1n$, for $n=1,\,2,\,3,\,\ldots$ ?

Oh nvm
I was thinking about countable and uncaountable.