In each of the following, determine whether the statement is true or false. If it is true, prove it. If it is false, give an example.
If $A \subset B$ and $x \notin B,$ then $x \notin A$
True
Let $A \subset B$ and $x \notin B$
To show: $x \notin A$
If possible, suppose $x \in A$
Then, $x \in B,$ which is a contradiction as $x \notin B$
$\therefore x \notin A$
Which of the following sets are finite or infinite.
$\{1,2,3 \ldots .\}$
Which of the following are sets ? Justify your answer.
The collection of all natural numbers less than $100 .$
Write the set $A = \{ 1,4,9,16,25, \ldots .\} $ in set-builder form.
In each of the following, determine whether the statement is true or false. If it is true, prove it. If it is false, give an example.
If $A \not\subset B$ and $B \not\subset C,$ then $A \not\subset C$
Which set is the subset of all given sets