Answer
$\text{Domain:}\;\{4\}$
$\text{Range:}\;\{6,8,10,12\}$
$\text{No, this relation is not a function.}$
Work Step by Step
The domain of a relation is the set of $x$ values for that function. In this relation, the set of $x$ values is $\{4\}$. The range of a relation is the set of $y$ values for that relation. In this relation the set of $y$ values is $\{6,8,10,12\}$. A relation is a function if each $x$ value has only one unique $y$ value. Since $4$, an element of the domain, is repeated with multiple $y$ values, this relation is not a function.
