1. Find the domain and the range of the relation shown on the graph to the right.
In this exercise, we have the graph of a relation in a Cartesian Coordinate System because it is formed by two perpendicular oriented lines. The horizontal line is called the x-axis while the vertical line is called the y-axis. So the domain of this relation is the set of all x-coordinates while the range is the set of all y-coordinates. Therefore:
- If we walk along the x-axis from left to right we realize that the domain is the set of all real numbers.
- If we walk along the y-axis from down to up we realize that the range is:
![(-\infty,-3) \cup (-1,\infty)](https://img.qammunity.org/2019/formulas/mathematics/high-school/2nun3qlphpmqbj7ijjby8k2xwdpkzr2a9l.png)
2. Use the vertical line test to determine whether the graph is the graph of a function.
A relation is a function if and only at most one
corresponds to a given
, meaning that the graph of a function can't match two or more different points with the same x-coordinate, that is, we can't have on the graph of a function two points or more points that are vertically above or below each other. Therefore, a relation is a function if and only if a vertical line intersects the graph of the function at most one point. Following this, we have drawn a vertical line below, so you can see that this line intersects the graph of the function in two points. Therefore, this relation is not a function.