Domain and Range (continued)

Domain and range can also be found by looking at an equation. For example, look at f(x) = 2x – 9. One way of analyzing this equation is to graph it. You can either use paper and pencil, a graphing calculator, or you can use the following graphing utility GCalc. Click on the GCalc image below. When the GCalc application opens, double click on the "Graph Plugin" to graph a linear equation. To adjust the window properties, go to the "Edit" menu and then "Properties". Click on the "View" tab and adjust the maximum and minimum x- and y-values.

Here is what the graph looks like:

Domain and Range

Notice that for this graph there are no x-values that will not eventually be covered by the graph. The same holds true for y-values. Therefore, the domain and range of f(x) = 2x – 9 is All Real Numbers. This means that any x- or y-value can be plugged into the equation.

Next: Section A, page 15

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