Question

Let A { l, 2, { 3, 4 5 }. $\emptyset \subset$ A Is the given statement is incorrect and why?

Answer 1

first of all, you should understand what is the meaning of $A\subset B$, $A\not\subset B$ and $A\in B$ ?

$A\subset B$ : A is subset of B. means, all elements of set A are elements of set B.

$A\not\subset B$ : A is not subset of B. means, all elements of setA are not elements of set B.

$A\in B$ : A belongs to B. means, set A is the element of set B.

now come to the question,
given, set A = {1, 2, {3, 4} , 5}.
we know one important thing is that the null set is a subset of each set.
so, we can write $\emptyset\subset A$
thus, the statement is correct.