Which relation is a function?

A.
{(1, 2); (1, 3); (3, 2); (4, 2)}

B.
{(1, 2); (2, 5); (3, 2); (4, 5)}

C.
{(1, 2); (2, 3); (3, 4); (1, 5)}

D.
{(1, 2); (2, 3); (3, 4); (2, 5)}
Question Resources

Question

Which relation is a function? 	
	
 
A.
	{(1, 2); (1, 3); (3, 2); (4, 2)}
	
 
B.
	{(1, 2); (2, 5); (3, 2); (4, 5)}
	
 
C.
	{(1, 2); (2, 3); (3, 4); (1, 5)}
	
 
D.
	{(1, 2); (2, 3); (3, 4); (2, 5)}
Question Resources

texaschic101 · Answer

a function cannot have 2 x values that are the same. They can have 2 y values that are the same, just not the x ones. Can you find the function now ?

kearsten · Answer

c

texaschic101 · Answer

C is not a function because it has 2 x values that are 1

imstuck · Answer

Do you know how to find out if a relation is a function?  The general rule is that it has to pass the vertical line test.  That means that when you draw a vertical line through the graph, it only passes through the line at one point.  No more than 1 place.  So we should graph these points to find that out.  It would be tedious to graph all of those here without the benefit of graph paper; do you know how to graph those points?  As long as you can graph them on your own and you apply the vertical line test, you should be good!

anonymous · Answer

What is the range of the relation?

{(1, 2), (2, 4), (3, 1), (4, 3)}

shamim · Answer

2,4,1,3

shamim · Answer

just second values of every pair

anonymous · Answer

There is absolutely nothing special at all about the numbers that are in a relation. In other words, any+bunch of numbers is a relation so long as these numbers come in pairs. 
The domain and range of a relation: 
The domain is the set of all the first numbers of the ordered pairs . In other words, the domain is all of the x-values. 

The range is the set of the second numbers in each pair, or the y-values.