Write the solution set of the equation ${x^2} + x - 2 = 0$ in roster form.
Let $A=\{1,2,3,4,5,6\} .$ Insert the appropriate symbol $\in$ or $\notin$ in the blank spaces:
$ 4\, ......... \, A $
Examine whether the following statements are true or false :
$\{ a\} \in \{ a,b,c\} $
State whether each of the following set is finite or infinite :
The set of circles passing through the origin $(0,0)$
Write down all the subsets of the following sets
$\{ 1,2,3\} $