State which of the following sets are finite or infinite :

$\{ x:x \in N$ and ${x^2} = 4\} $

State which of the following sets are finite or infinite :

$\{ x:x \in N$ and $(x - 1)(x - 2) = 0\} $

Write the following sets in roster form :

$A = \{ x:x$ is an integer and $ - 3 < x < 7\} $

Write the following as intervals :

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

Given the sets $A=\{1,3,5\}, B=\{2,4,6\}$ and $C=\{0,2,4,6,8\},$ which of the following may be considered as universal set $(s)$ for all the three sets $A$, $B$ and $C$

$\{ 0,1,2,3,4,5,6\} $

Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.