The smallest set $A$ such that $A \cup \{1, 2\} = \{1, 2, 3, 5, 9\}$ is
$\{2, 3, 5\}$
$\{3, 5, 9\}$
$\{1, 2, 5, 9\}$
None of these
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$1 \in A$
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{\varnothing\} \subset A$
List all the elements of the following sers :
$C = \{ x:x$ is an integer ${\rm{; }}{x^2} \le 4\} $
Which of the following is the empty set
Write the following as intervals :
$\{ x:x \in R, - 12\, < \,x\, < \, - 10\} $