Write the following as intervals :

$\{ x:x \in R,3\, \le \,x\, \le \,4\} $

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 $\} $

Let $A=\{1,2,3,4,5,6\} .$ Insert the appropriate symbol $\in$ or $\notin$ in the blank spaces:

$ 2 \, ....... \, A $

Write the following sets in roster form :

$\mathrm{F} =$ The set of all letters in the word $\mathrm{BETTER}$

Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?

$\varnothing \subset A$

The number of elements in the set $\{x \in R :(|x|-3)|x+4|=6\}$ is equal to