Question

State in the case whether $A\subset$ or $A⊈B$.
$A=\{1,2,3\},B=\{1,2,4\}$

Answer 1

The symbol $\subseteq$ means "is a subset of". The symbol $\subset$ means "is a proper subset of".

Since, $3\in A$ does not belong to $B$

So, in

$A=\{1,2,3\},B=\{1,2,4\}$

$A⊈B$