Latex symbol not in which means “is not an element of”, “is not a member of” or “does not belong to” is the command: /notin $x\notinA$ which gives $x \notin A$ Examples Here are few examples: $\forallx\notin]-1,+\infty[$ $\forall x \notin ]-1,+\infty[$ $\for...
The symbol used to denote inequation (when items are not equal) is a slashed equal sign ≠ (U+2260). In LaTeX, this is done with the "\neq" command.