Which of the following are sets ? Justify your answer.
The collection of all the months of a year beginning with the letter $\mathrm{J}.$
The collection of all months of a year beginning with the letter $\mathrm{J}$ is a well-defined collection of objects because one can definitely identity a month that belongs to this collection.
Hence, this collection is a set.
Write the following intervals in set-builder form :
$\left[ {6,12} \right]$
Write the following sets in the set-builder form :
$\{ 3,6,9,12\}$
List all the elements of the following sers :
$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $
Write the following sets in roster form :
$\mathrm{F} =$ The set of all letters in the word $\mathrm{BETTER}$
State which of the following sets are finite or infinite :
$\{ x:x \in N$ and ${x^2} = 4\} $