- #1

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*(A x B) U (X x Y) = (A U X) x (B U Y) is not valid for all choices of sets A,B,X,Y.*

I started out by saying that

let (x,y) be in A and B or

let (x,y) be in X and Y

Since x is in A and y is in B

--> (x,y) = (A x B)

Since x is in X and y is in Y

--> (x,y) = (X x Y)

Can I go on to say that since x is in A and x is in A

x is a subset of (A U X)?

How do I prove that this is not true?