Let k = 0 + 5.
A) Show the union of k countable sets is countable.
any help will be useful
Proof. Let two sets A={an:n∈N} and B={bm:m∈N}. Then we can define a new sequence c, such that, the first n elements in c are n elements of A and next m elements are elements of B, and then duplicates are
So
, and p<= m+n.
Hence for any 2 sets, of length n,m which are countable, their union, A U B is also countable.
C1 U C2 is countable,
Let C1 U C2 U... U C(k-1) is also countable, then by induction, we can say that C1 U C2 U ... Ck is also countable.
Thinking logically, if we can count number of elements in 2 or more finitte different sets, then we can also count the number of elements of their unions.
I hope it helps. For any doubt, feel free to ask in comments, and give upvote if u get the answer.
Let k = 0 + 5. A) Show the union of k countable sets is countable....
Give an example to show that a union of countable sets need not
be countable. (Obviously your example must involve infinitely many
sets.)
4. Give an example to show that a union of countable sets need not be countable. (Obvi- ously your example must involve infinitely many sets.)
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is the countable union of closed sets.
Fo # Gs, and GS UFO # Gso n Fos.
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all parts A-E please.
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