Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$\text{False}$
If a relation is to be a function, each element in the domain set must correspond to one element exactly in the range set. Consider the relation defined by the set of ordered pairs $\{(1,2),(1,3)\}$. Here, the domain element 1 corresponds to two range elements 2 and 3. So, this relation is not a function. Hence the given statement is $\text{false}$.