TI-83 Calculator Usage

 

Using the TI-83 to graph functions:

When using the TI-83 to graph functions, you should be aware of how the graphing calculator does this. To graph a function, the calculator plots points on the screen, and then connects the points it has plotted. This does NOT mean that the graph will be 100% accurate. You will still need to interpret the graph, and make sure that the calculator has produced a reasonable picture. Most importantly, the TI-83 will only graph functions – if it produces a graph that does not look like the graph of a function (i.e. doesn’t pass the vertical line test) then you have a problem that you need to deal with.

To begin graphing a function, you will first need to set the range of values for the X-coordinates and the Y-coordinates. This is done by going into the [WINDOW] screen and entering:

Xmin = (the smallest X-value you are interested in)

Xmax = (the largest X-value you are interested in)

Xscl = (the spacing you want between grid marks for the X-values)

Ymin = (the smallest Y-value you are interested in)

Ymax = (the largest Y-value you are interested in)

Yscl = (the spacing you want between grid marks for the Y-values)

Xres = (an integer between 1 and 8 – the lower the number, the better the resolution)

Then you will want to go into the [Y=] screen and enter the function to be graphed.

After this is done, press [GRAPH]

Note: If the graph doesn’t show up on your screen now, there are two common causes:

  1. The graph isn’t turned on (the "=" sign isn’t highlighted in the [Y=] screen). To fix this problem, trace to the "=" sign, and hit [ENTER] to change it’s highlighted status.
  2. You haven’t chosen a good viewing [WINDOW]. One way to fix this to continually use the [Zoom] Option 3: Zoom Out. This will continue to give you a larger rectangle until you can see the graph on it. Once you can see the graph, you should have a better idea what [WINDOW] you need to use.

You may now use the [TRACE] key and arrows to trace along the graph and read off points on the graph. But be careful! To accurately find the values for x- and y-intercepts, maximum and minimum points, and points of intersection, you need to use the [2nd] [CALC] function of your calculator. See the instructor for further information on this feature.