# Domain and Range

Author:
K Redmond
Move any of the black points to change the domain and range of the graph. If the graph does not appear, you may need to adjust the points. Reset the construction by pressing the refresh button in the top left.
How do you find domain? The domain is the set of all x-values of the function. The domain is generally written in either interval form (as is written in the applet above) or inequality form. The reason for this is that functions do not include just individual whole numbers, but all decimal values in between, so we write the interval as starting at the smallest included x-value and ending at the largest included x-value. This is usually seen as the left most point of graph and the right most point of the graph. How do you find the range? The range is the set of all y-values of the function. The range is found in a similar fashion to the domain, but instead of writing the interval as beginning at the smallest x-value and ending at the largest x-value, we write it as starting at the smallest y-value and ending at the largest y-value. This is usually seen as the y-value at the lowest point of the graph, and the y-value at the highest point of the graph. Remember: the graph is the drawn line or curve.