Question:
Let $A=\{3,4,5,6\}$ and $R=\{(a, b): a, b \in A$ and $a (i) Write $\mathbf{R}$ in roster form. (ii) Find: dom (R) and range (R) (iii) Write $\mathbf{R}^{\mathbf{- 1}}$ in roster form
Solution:
(i) R = {(3, 4), (3, 5), (3, 6), (4, 5), (4, 6), (5, 6)}
(ii) The domain of $R$ is the set of first co-ordinates of $R$
Dom(R) = {3, 4, 5}
The range of $R$ is the set of second co-ordinates of $R$
Range(R) = {4, 5, 6}
(iii) $R^{-1}=\{(4,3),(5,3),(6,3),(5,4),(6,4),(6,5)\}$