A relation that is a function This relation is definitely a function because every x-value is unique and is associated with only one value of y. So for a quick summary, if you see any duplicates or repetitions in the x-values, the relation is not a function. How about this example though? Showing top 8 worksheets in the category - Answer Key. Some of the worksheets displayed are Instructional work, Teaching transparency work chemistry answers chapter 3, Earths interior work answer key, Area of a shape, Area of a triangle t1l1s1, Run on sentence answer key, Magnetic attraction, Range 1. Understanding Speed, Distance and Time. Linear functions are frequently used to represent a change in speed proportional to distance and time. These types of graphs help children understand the relationship between speed, distance and time, concepts which they will need to master in order to gain confidence in math and science.