This section covers:

Beginning with your first Algebra course, you’ll probably get introduced to a **graphic display calculator** or **graphing display calculator** (**GDC**). I prefer the Texas Instruments® TI-83 or TI-84 Plus. The software I’ve used to create these graphs is the “online” version of this calculator, TI-SmartView™ Emulator Software for the TI-84 Plus Family, which can be downloaded from the Texas Instruments web site.

**Note**: most pictures show the TI-84 C (Color) Silver Edition calculator.

First, turn the calculator **ON**, and make sure the calculator is in **FUNC** mode (for “function”): hit **MODE** (in the upper left – to the right of the 2^{nd} button). On the 4^{th} line, make sure FUNC is highlighted:

**Note:** if your graphing calculator ever gets “stuck” and doesn’t seem to be graphing, you can hit to turn it off, and then to turn it back on again.

Also, if you need to clear (reset) the calculator, you can use to clear the RAM in the calculator. But **be careful** doing this, since you will lose any programs you’ve created in the calculator.

# Basic Graphing

To create the graph “**y = 10x**”, press the following.

You may need to press **CLEAR** to clear out any equations in any of the “**Y =**” fields.

You can put additional equations in** “Y _{2}=” **and so on

**.**It’s as easy as that!

You have to be careful when you look at these graphs, since the scales may not be what you want. Note that the *x*-axis has a different scale than the *y*-axis.

If you don’t see the graph in the middle of the screen, you can enter **ZOOM 6 **(ZStandard)to get the standard window (typically –10 to 10 on both axes).** **You can also use the cursors to move down to ZStandard after you press **ZOOM**.

If you still don’t see what you want in the graph, try **ZOOM** **0** (ZoomFit), or go to **WINDOW** and enter appropriate values for **Xmin**, **Xmax**, **Ymin**, and **Ymax**, by looking at your graph and seeing what axis or axes you need to make larger or smaller. I would leave **Xscl = 1**.

For example, in the graph above, we may want to reduce the size of the X window to see more of the graph. The Xmin was changed from “–10” to “–4”, and the Xmax was changed from “10” to “4”.

Also note that the graph is not square; the *x*-axis is scaled differently than the *y*-axis. You can make the graph square by trying **ZOOM** **5** (ZSquare).

You can hit **TRACE **and move the cursors to see the different values of *x* and *y* on the graph.

You can also go to the **TABLE** (2^{nd} **GRAPH**) to see actual points, and scroll up and down with the cursor. If you want to start from a different point, or want to change the delta X (how often the *x* values are displayed, for example, by 1’s or by .5’s), you push **TBLSET** (2^{nd} **WINDOW**):

(Note that it gets a little more complicated if you want graph a vertical line like “*x* = 3”; you can do this with another mode (**PAR**), but you usually won’t be graphing these vertical lines).

# Inequalities

We can also display inequalities on the calculator. Use “**Y =**” to input the equation in the calculator, and then use the cursor to scroll left to the “**Y =**”. When the cursor is over the “**\**”, hit **ENTER **until you see (for less than) or (for more than). (For the TI-84 C Calculator), you’ll have to scroll down over where you can change the colors). You can put more than one inequality by using **“Y _{2} =”** and so on.

To put the graphing calculator back to “**=**”, hit **ENTER** the same way until you see “**\**” again.

Here’s an example for y < 2x + 4 and y > 3:

This should give you a start in getting familiar with the graphing calculator; I will provide more instructions in each section where we use it.

If you are working on Quadratics, where the graphing calculator is typically introduced, go to **Using the Graphing Calculator to Find the Vertex and Solve Quadratics** in the **Introduction to Quadratics** section.

**Practice on the Graphing Calculator – you can’t hurt it!**

On to Intermediate Algebra, and **Systems of Linear Equations** – you are ready!