Which of the following are sets ? Justify your answer.
The collection of ten most talented writers of India.
The collection of ten most talented writer of India is not a well-defined collection because the criteria for determining a writer's talent vary from person to person.
Hence, this collection is not a set.
State whether each of the following set is finite or infinite :
The set of lines which are parallel to the $x\,-$ axis
Let $A=\{1,2,3,4,5,6\} .$ Insert the appropriate symbol $\in$ or $\notin$ in the blank spaces:
$ 2 \, ....... \, A $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{ 3,4\} \subset A$
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and ${x^2} = 4\} $
Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.