Question:
If $R=\left\{(x, y): x^{2}+y^{2} \leq 4 ; x, y \in Z\right\}$ is a relation on $Z$, write the domain of $R$.
Solution:
Domain of R is the set of values of x satisfying the relation R.
As x must be an integer, we get the given values of x:
$0, \pm 1, \pm 2$
Thus,
Domain of $R=\{0, \pm 1, \pm 2\}$