Which of the following is the empty set
$\{ x:x$ is a real number and ${x^2} - 1 = 0\} $
$\{ x:x$ is a real number and ${x^2} + 1 = 0\} $
$\{ x:x$ is a real number and ${x^2} - 9 = 0\} $
$\{ x:x$ is a real number and ${x^2} = x + 2\} $
Make correct statements by filling in the symbols $\subset$ or $ \not\subset $ in the blank spaces:
$\{ x:x$ is an even natural mumber $\} \ldots \{ x:x$ is an integer $\} $
Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$
$\{0,1,2,3,4,5,6,7,8,9,10\}$
Which of the following sets are finite or infinite.
$\{1,2,3, \ldots 99,100\}$
List all the elements of the following sers :
$C = \{ x:x$ is an integer ${\rm{; }}{x^2} \le 4\} $
Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.