The relations in 3, 4, and 6 are functions
3 and 4 are one to one function
6 is one to many function
5. is not a function
What is a function?
In mathematics, a function is a relation between a set of inputs and a set of possible outputs, such that each input is related to exactly one output.
A function assigns exactly one output value to each input value based on a specific rule or set of rules.
The relation is option 5, is a mapping diagram. It has x = -2 as being equal to 1 and 3. Hence not a function