Answer:
Relation 1- function
Relation 2- not a function
Relation 3- Function
Relation 4- not a function
Explanation:
Steps my teacher taught us to find a function were to first see if there are x values that repeated like in relation 4 you see y repeated 3 times making it not a function. the rule is that you can many x going to one y, but not many ys going to one x. it's kinda hard to explain so I hope it made sense!