There exists $x\in B$ such that $x\notin A.$

logic

Let $A$ and $B$ be two sets. Statement: There exists $x\in B$ such that $x\notin A.$

My Question: What is the negation of the above statement?

My Answer is: For every $x\in B,$ we have $x\in A,$ that is $B\subset A.$ Is this correct?

Best Answer

Edit because the OP changed the question. This is an answer to the one asked.

The assertion you want to negate is the definition of "proper subset":

$A$ is a subset of $B$ and there is some $b \in B$ that's not in $A$.

The negation is

Either $A$ is not a subset of $B$, or (if it is a subset) it is all of $B$.

General remark for this kind of question. I think it's much easier to understand both question and answer with words instead of symbols where possible.