Which of the following are examples of the null set
$\{ x:x$ is a natural numbers, $x\, < \,5$ and $x\, > \,7\} $
Write the set $\left\{\frac{1}{2}, \frac{2}{3}, \frac{3}{4}, \frac{4}{5}, \frac{5}{6}, \frac{6}{7}\right\}$ in the set-builder form.
Write the following intervals in set-builder form :
$\left[ { - 23,5} \right)$
State whether each of the following set is finite or infinite :
The set of letters in the English alphabet
The set $A = \{ x:x \in R,\,{x^2} = 16$ and $2x = 6\} $ equals