Answer:
Depending on how the input of each function defined,
- The first choice
,
- The third choice
- The fourth choice
might be functions.
Step-by-step explanation:
A function between two sets (domain and range) should
- be defined for all elements in the domain, and
- map each element from the domain to exactly one element in the range.
The second choice can't be a function since the element from the domain is mapped to more than one element in the range.
Keep in mind that a function should be defined for all elements in its domain. For the first relation to be a function, its domain needs to be . Similarly, the domain for the third and fourth relations should be
and