The element 15 has two arrows pointing to both 7 and 9. The only thing I am after is to observe if an element in the domain is being “greedy” by wanting to be paired with more than one element in the range. This is a great example of a function as well.Įxample 3: Is the relation expressed in the mapping diagram a function? What do you think? Does each value in the domain point to a single value in the range? Absolutely! There’s nothing wrong when four elements coming from the domain are sharing a common value in the range. That is, even though the elements 5 and 10 in the domain share the same value of 2 in the range, this relation is still a function.nullĮxample 2: Is the relation expressed in the mapping diagram a function? However, it is okay for two or more values in the domain to share a common value in the range. Let’s go over a few more examples by identifying if a given relation is a function or not.Įxample 1: Is the relation expressed in the mapping diagram a function?Įach element of the domain is being traced to one and only element in the range.
#EXAMPLE OF ONTO VS ONE TO ONE HOW TO#
The relation is now clearly a function! Examples of How to Determine if a Relation is also a Function This table can be cleaned up by writing a single copy of the repeating ordered pairs. The point (1,5) shows up twice, and while the point (3,-8) is written three times. Yes, we have repeating values of x but they are being associated with the same value of y. How about this example though? Is this not a function because we have repeating entries in x?īe very careful here. So for a quick summary, if you see any duplicates or repetitions in the x-values, the relation is not a function. This relation is definitely a function because every x-value is unique and is associated with only one value of y. Just like a relation, a function is also a set of ordered pairs however, every x-value must be associated to only one y-value. On the other hand, a function is actually a “special” kind of relation because it follows an extra rule. Since we have repetitions or duplicates of x-values with different y-values, then this relation ceases to be a function. Suppose we have two relations written in tables, When listing the elements of both domain and range, get rid of duplicates and write them in increasing order. We may describe it as the collection of the second values in the ordered pairs.