Question:
Let $R=\left\{(x, y): x, y \in Z\right.$ and $\left.x^{2}+y^{2} \leq 4\right\}$.
(i) Write $\mathbf{R}$ in roster form.
(ii) Find dom (R) and range (R).
Solution:
Given: $R=\left\{(x, y): x, y \in Z\right.$ and $\left.x^{2}+y^{2} \leq 4\right\}$
(i) R is Foster Form is
$R=\{(-2,0),(-1,-1),(-1,0),(-1,1),(0,-2),(0,-1),(0,0),(0,1),(0,2),(1,-1),(1,0),(1,$, 1), $(2,0)\}$
(ii) $\operatorname{Dom}(R)=\{-2,-1,0,1,2\}$
Range $(R)=\{-2,-1,0,1,2\}$