Answer: The first one.
Explanation:
- A relation between two set is said to be a function if each input has a single output.
- The set of input value is known the Domain of a function.
- The set of output is known as the Range of the function.
The first mapping of f is not a function because there are 2 output values for a single input vale of 3.
Hence, the first mapping f is not a function.
Rest of other mapping are function.