How do you tell if the relation is a function
To determine if relation is a function:
A relation is said to be a function if for each value of the independent variable ; there is only one possible value of , i.e. the dependent variable. In other words we can say, for each input value of , there should be only one output value.
We can also check graphically whether the relation is a function or not using a vertical line test. Draw a vertical line anywhere, if the vertical line cross the graph at exactly one point then it is a function.
When we observe a set of pairs of numbers (set of ordered pairs) in the form and if any of the values are repeated, then it is not a function. Thus we can say that all functions are relations, but not all the relations are functions.
Hence, we can tell if the relation is a function by above three ways.