Domain and range

Question

Identify the domain and the range of each relation. Is this a function or not.

{(5,4),(7,6),(9 8),(11,10)}

Answer 1

Hi Meliisa,

 

This relation is a function.

 

Correction:

For each value for the domain, there is exactly ONE value in the range.

If we list all x coordinates in a set, and there are no repeating numbers, it is a function. In our case

x∈{5, 7, 9, 11}.

So far, if there are no points with the same FIRST coordinate, the relationship is a function.

 

If for different x you have different y, then the function is called One-to-One function.

Answer 2

Hi Melisa,

 

The domain consists of all the inputs for a relation.  Inputs correspond to the x-coordinates.  So, the domain for this relation is the set {5, 7, 9, 11}

 

The range consists of all the outputs for a relation.  Outputs correspond to the y-coordinates.  So, the range for this relation is the set {4, 6, 8, 10}

 

A relation is a function if each input is related to only one output.  Since none of the x-coordinates are related to more than one y-coordinate the relation is a function.

 

 

 

By the way, if the second point was (5, 6) instead of (7, 6), then the relation would not be a function because 5 would be related to both 4 and 6.  

 

Hope this helps.  :)