The domain and range indicate some boundaries and constraints of a function. The domain of a function is the set of x values for which the function returns a result. The range of a function is the set of all y values returned over the domain. Different types of functions have different trends that determine their domain and range. On a graphing calculator, you can determine the domain and range visually or by looking at the graph's table.
Enter the function in your graphing calculator's function menu. On a Casio fx-9750GII or related model, press "Menu" and select "Graph." On a TI-84 plus or related model, press "Y=." On an HP-50g, hold the left shift button and then press "F1". Then, press "F2" to enter a function.
View the graph of the function. On a Casio fx-9750GII, press "F6" after entering your function. On a TI-84 plus, press "Graph." On an HP-50g, press "F6" after entering the function. Sometimes, you can get a sense of the domain and range just by looking at the graph. For example, the function y=x^2 is a parabola with a vertex at the origin. Its domain is all real numbers, and its range is from zero to infinity.
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Trace the function. On a Casio fx-9750GII, press "Shift" and "F1." Then select "Trace." On a TI-84 plus, press "Trace." On an HP-50g, press "F3." This feature will give you a sense of the general behavior of the function. For example, the y values of y=log(x) tend towards negative infinity as x goes to zero. Because x never equals zero, the domain of the function is all positive real numbers. As you trace the function and monitor y values, you will notice that the range includes all real numbers.
Look at the table of values for your graph. On a Casio fx-9750GII, press "Exe" while tracing the line. This command will store values. Press "Optn" and then "F1" to view the table. On a TI-84 plus, press "2nd" and then "Trace." On an HP-50g, press the left shift button and then "F6." The table will help confirm the trends that you viewed while tracing the graph.