Let A and B be sets. Suppose A contains at least 2 elements. Prove that...
Let A and B be sets. Suppose A contains at least 2 elements. Prove that if every proper subset of A is a subset of B, then A is a subset of B. (Hint: what does it mean for a subset of A with size one to be a subset of B?)
What is an example and explanation to demonstrate why the above proof can be false if A contains only 1 element.
When I attempted this question on my own, I couldnt even get started. I follow the one answer that was already provided but I'm not sure how you would write this using symbols. Something like: , xED so could be XEA but D does not equal A. If xEA, Then xEB. But this reasoning must be flawed as I am not taking into account the hint.