Let $A, B$ and $C$ be three sets. If $A \in B$ and $B \subset C$, is it true that $A$ $\subset$ $C$ ?. If not, give an example.
No. Let $A=\{1\}, B=\{\{1\}, 2\}$ and $C=\{\{1\}, 2,3\} .$ Here $A \in B$ as $A=\{1\}$ and $B \subset C$. But $A \not\subset C$ as $1 \in A$ and $1 \notin C$
Note that an element of a set can never be a subset of itself.
Write the following sets in the set-builder form :
$\{ 1,4,9 \ldots 100\} $
If a set $A$ has $n$ elements, then the total number of subsets of $A$ is
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and ${x^2} = 4\} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\{ \{ 3,4\} \} \subset A$
Write the following sets in roster form :
$D = \{ x:x$ is a prime number which is divisor of $60\} $