PIECEWISE-DEFINED FUNCTIONS
ON A GRAPHING CALCULATOR

You can use your graphing calculator to graph so-called “piecewise-defined” functions, such as:

Using the key, you enter the two “pieces,” one as Y1 and the other as Y2. When you are finished, they will look like this:

Y1 = 2X-2/(X<2)
Y2 = X^2-8/(X>2)

Notice the “slash” and the inequality in parentheses after each function. The slash is merely the division symbol and is entered simply by pressing the key. Likewise for the parentheses.

To get the inequality symbols, press (gotten by pressing ) which will give you this screen:

Then simply select the desired inequality. If you do all this correctly, the screen should now look like this:

Enter the second function in a similar manner. The screen should now look like this:

Pressing the key yields the following result:


“DOUBLE” INEQUALITIES

With one addition, the same technique can be used to graph a function (or a piece of a function) whose domain is defined by a so-called double inequality, such as:

The first thing that must be done is to split the double inequality into two separate inequalities joined by a logical and:

We enter the function into the same as before, and when we get to the logical and, we need to access the list of logical operators. As before, press (gotten by pressing ), then use the right arrow key () to move to the LOGIC screen:

Select the appropriate logical operator (in this case and) and proceed as before. The screen and the resulting graph should look like those shown below:


Using the or operator, you can also graph functions such as:

Using the same techniques as above, the screen and the resulting graph should look like those shown below: