The number of proper subsets of the set $\{1, 2, 3\}$ is

List all the elements of the following sers :

$A = \{ x:x$ is an odd natural number $\} $

State whether each of the following set is finite or infinite :

The set of circles passing through the origin $(0,0)$

Which of the following are sets ? Justify your answer.

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Write the following intervals in set-builder form :

$\left[ {6,12} \right]$

In the following state whether $A=B$ or not :

$A=\{a, b, c, d\} ; B=\{d, c, b, a\}$