State which of the following sets are finite or infinite :
$\{ x:x \in N$ and ${x^2} = 4\} $
Which of the following is a true statement
Write the set $\{ x:x$ is a positive integer and ${x^2} < 40\} $ in the roster form.
How many elements has $P(A),$ if $A=\varnothing ?$
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and $2x - 1 = 0\} $