Final answer:
A function describes a relationship between two sets of values, where each input value is associated with only one output value. To determine if a relation is a function, check if each input value has only one corresponding output value.
Step-by-step explanation:
A function describes a relationship between two sets of values, where each input value (or domain value) is associated with only one output value (or range value). In other words, it assigns exactly one element of the range to each element of the domain. This is often represented as an equation or a graph.
For example, consider the relation between the cost of apples and the number of apples bought. If we represent the cost of apples as 'C' and the number of apples bought as 'N', a function would ensure that for each value of 'N', there is only one corresponding value of 'C'. In this case, if we buy 2 apples, the cost may be $1, but if we buy 5 apples, the cost may be $3.
If Neil wants to determine if a relation is a function, he could examine whether each input value has only one corresponding output value. If any input value has more than one corresponding output value, then the relation is not a function.