Question

Write set $A$ in Roster form : $A=\{x:x=y+3,y\in N$ and $y>3\}$.

Answer 1

In Roster form, we write the set with the elements within curly brackets with no elements repeating.
Hence required set can be got by substituting various values of $y$ from 4 onwards and getting the values of $x$ such as $=$ $\{4+3,5+3,6+3,7+\mathrm{3....}\}$ $=$ $\{7,8,9,\mathrm{10....}\}$