Identifying functions

Are the following sets of ordered pairs functions?
1. (4,3), (2,6), (-3,4), (-2,5)
2. (4,5), (4,-3), (2,6), (3,2)
3. (3,6), (2,6), (5,3), (1,2)
Which of the following is a function?
Using the table of values to answer the questions below:
1. X value -5 -3 -1 1 3
  
  Y value 3 1 -1 -2 -3
  
  Express the relations using ordered pairs, mapping notations and determine is it a function
2. X value -5 -3 -1 1 3
  
  Y value 2 2 -1 -2 -3
  
  Express the relations using ordered pairs, mapping notations and determine is it a function
3. X value -5 -5 -1 1 3
  
  Y value 2 3 2 3 -3
  
  Express the relations using ordered pairs, mapping notations and determine is it a function