How to Graph Functions on the TI-84 Plus
After you have entered functions into the TI-84 Plus graphing calculator, the calculator has a variety of features that help you painlessly graph a function as well.
Use the following steps to graph the functions:
Turn off any Stat Plots that you don’t want to appear in the graph of your functions.
The first line in the Y= editor tells you the graphing status of the Stat Plots. If Plot1, Plot2, or Plot3 is highlighted, then that Stat Plot will be graphed along with the graph of your functions. If it’s not highlighted, it won’t be graphed.
To turn off a highlighted Stat Plot in the Y= editor, use the
keys to place the cursor on the highlighted Stat Plot and then press [ENTER]. The same process is used to highlight the Stat Plot again in order to graph it at a later time.
When you’re graphing functions, Stat Plots can cause problems if they’re turned on when you don’t really want them to be graphed. The most common symptom of this problem is the ERR: INVALID DIM error message — which by itself gives you almost no insight into what’s causing the problem. So if you aren’t planning to graph a Stat Plot along with your functions, make sure all Stat Plots are turned off.
Press [2nd][ZOOM] to access the Format menu.
Set the format for the graph by using the
keys to place the cursor on the desired format, and then press [ENTER] to highlight it.
Press [WINDOW] to access the Window editor.
After each of the window variables, enter a numerical value that is appropriate for the functions you’re graphing. Press [ENTER] after entering each number.
Here is the Window editor when the calculator is in Function mode. The items in this menu determine the viewing window for your graph — in particular, how the x- and y-axes look on the screen. You must set the following variables in this editor:
Xmin and Xmax: These are, respectively, the smallest and largest values of x in view on the x-axis.
If you don’t know what values your graph will need for Xmin and Xmax, press [ZOOM] to invoke the ZStandard command. This command automatically graphs your functions in the Standard viewing window. You can then, if necessary, use the other Zoom commands to get a better picture of your graph.
Xscl: This is the distance between tick marks on the x-axis. (Go easy on the tick marks; using too many makes the axis look like a railroad track. Twenty or fewer tick marks makes for a nice looking axis.)
Ymin and Ymax: These are, respectively, the smallest and largest values of y that will be placed on the y-axis.
If you have assigned values to Xmin and Xmax but don’t know what values to assign to Ymin and Ymax, press [ZOOM] to invoke the ZoomFit command. This command uses the Xmin and Xmax settings to determine the appropriate settings for Ymin and Ymax, and then automatically draws the graph. It does not change the Yscl setting.
(You must return to the Window editor, if necessary, to adjust this setting yourself.)
Yscl: This is the distance between tick marks on the y-axis. (As with the x-axis, too many tick marks make the axis look like a railroad track. Fifteen or fewer tick marks is a nice number for the y-axis.)
Xres: This setting determines the resolution of the graph. It can be set to any of the integers 1 through 8. When Xres is set equal to 1, the calculator evaluates the function at each of the 94 pixels on the x-axis and graphs the result. If Xres is set equal to 8, the function is evaluated and graphed at every eighth pixel.
Xres is usually set equal to 1. If you’re graphing a lot of functions, it may take the calculator a while to graph them at this resolution, but if you change Xres to a higher number, you may not get an accurate graph.
If it’s taking a long time for the calculator to graph your functions, and this causes you to regret setting Xres equal to 1, press [ON] to terminate the graphing process. You can then go back to the Window editor and adjust the Xres setting to a higher number.
Press [GRAPH] to graph the functions.