TI-84 Graphing Guide: Every Key You Need
About this guide. Grafolyn is an independent online graphing calculator. We are not affiliated with, endorsed by, or connected to Texas Instruments Incorporated, and this site is not a TI-84 emulator. This page is a reference for people using the physical calculator, written because exams often permit it and nothing else. TI-84 and TI are trademarks of Texas Instruments Incorporated.
The TI-84 Plus hides most of its useful functions behind the 2nd key, which is why a calculator people own for years still produces blank screens and cryptic errors. This is the keystroke reference, organised by what you are trying to do.
Entering a function
- Press Y=, the leftmost key in the top row. You get a list of slots labelled Y1 through Y0.
- Type the function. Use the X,T,θ,n key for the variable — the one directly below MODE. This is the most common beginner mistake: the letter X from ALPHA looks identical on screen but is a different symbol and will not graph.
- Use the ^ key for powers, and x² for squares.
- Press GRAPH.
To turn a function off without deleting it, move the cursor onto the
= sign next to it and press ENTER. The equals sign
stops being highlighted and that function is skipped.
| To type | Press |
|---|---|
| Negative number | (-), not the subtraction key. They are different. |
| Square root | 2nd x² |
| Absolute value | MATH › NUM › 1:abs( |
| Fraction template | ALPHA Y= (on OS 2.53 and later) |
| π | 2nd ^ |
| e | 2nd ÷ |
Setting the window
Press WINDOW to set the visible region directly. Six values matter:
- Xmin, Xmax: left and right edges.
- Xscl: spacing of the tick marks on the x-axis.
- Ymin, Ymax: bottom and top edges.
- Yscl: tick spacing on the y-axis.
Xmin must be less than Xmax, and Ymin less than Ymax, or you get
ERR: WINDOW RANGE. Set Xscl to something sensible: leaving it
at 1 while viewing −1000 to 1000 draws two thousand tick marks and turns the
axis into a solid black line.
The ZOOM menu
Faster than setting the window by hand. Press ZOOM and pick a number.
| Key | Name | What it does |
|---|---|---|
| 4 | ZDecimal | Makes TRACE step in neat 0.1 increments |
| 5 | ZSquare | Equalises the axis scales, so circles look circular |
| 6 | ZStandard | Resets to −10 to 10 on both axes. The panic button. |
| 7 | ZTrig | A window suited to trigonometric functions |
| 9 | ZoomStat | Fits the window to the data in your stat lists |
| 0 | ZoomFit | Keeps the x range and fits the y range to the function |
ZStandard then ZoomFit is the fastest fix for a blank screen: reset to a known window, then let the calculator work out a vertical range that actually contains the curve.
The CALC menu: zeros, maxima, intersections
Press 2nd then TRACE. This is the menu that answers most homework questions, and it is the one students most often do not know exists.
2:zero — find an x-intercept
- Choose 2:zero.
- Left Bound? Move the cursor to a point left of the crossing and press ENTER.
- Right Bound? Move right of it and press ENTER.
- Guess? Press ENTER again.
The bounds must bracket exactly one crossing. If the answer looks wrong, you probably enclosed two.
3:minimum and 4:maximum — find a turning point
The same three-press pattern: left bound, right bound, guess.
5:intersect — where two curves cross
- Have both functions in the Y= list and visible.
- Choose 5:intersect.
- First curve? ENTER.
- Second curve? ENTER.
- Guess? ENTER.
With more than two functions on screen, use the up and down arrows to select which two before pressing ENTER.
1:value — evaluate at a specific x
Choose 1:value, type the x-value, press ENTER. The x must be inside the current window or it refuses.
Using the table
Press 2nd then GRAPH to see a table of values. Press 2nd then WINDOW for TBLSET to control it:
- TblStart: the first x-value.
- ΔTbl: the step between rows.
- Indpnt: Ask lets you type individual x-values instead of stepping automatically, which is quicker when you want three specific points.
How this compares with graphing online
Both have their place, and it is worth being clear about which is which.
| TI-84 Plus | Graphing in a browser | |
|---|---|---|
| Allowed in exams | Yes, on most | No, never |
| Speed of entry | Slower; menus and modes | Faster; type and it draws |
| Screen | Small, low resolution | As large as your display |
| Finding roots | One at a time, with bounds | All of them at once |
| Sharing your work | Photograph the screen | A link, or an exported image |
| Cost | Around $100 to $130 | Free |
The practical approach: use whichever is quicker while you are learning, and make sure you can do it on the TI-84 before the exam. Being fluent with 2nd TRACE under time pressure is a real skill, and it is not one you can pick up on the day.
Error messages decoded
| Message | Usual cause | Fix |
|---|---|---|
| ERR: WINDOW RANGE | Xmin is not less than Xmax, or the same for Y | ZOOM 6 |
| ERR: INVALID DIM | A stat plot is on with empty or mismatched lists | 2nd Y=, then 4:PlotsOff |
| ERR: SYNTAX | Usually the subtraction key used for a negative | Use (-) for negatives |
| ERR: DOMAIN | An input outside the function's domain | Check for a negative under a root, or log of a non-positive |
| ERR: NO SIGN CHNG | The bounds for zero do not bracket a crossing | Choose bounds either side of the crossing |
| Blank screen, no error | The curve is outside the window | ZOOM 6, then ZOOM 0 |
Keystrokes vary slightly between operating system versions. If a menu item is not where this page says, check MODE for a newer layout, or consult the guidebook Texas Instruments publishes for your model.
Questions
Why is my TI-84 screen blank after pressing GRAPH?
Almost always the window. Press ZOOM then 6 for ZStandard to reset to a −10 to 10 view, or ZOOM then 0 for ZoomFit, which picks a vertical range that fits the function across the current x range.
What does ERR: INVALID DIM mean?
Usually a stat plot is switched on while its lists are empty or of different lengths. Press 2nd then Y= to open STAT PLOT, then choose 4:PlotsOff and press ENTER.
How do I enter x on a TI-84?
Use the X,T,θ,n key just below the MODE key. It types the right variable for whichever graphing mode you are in. Typing X from the ALPHA menu looks the same but is a different symbol and will not graph.
How do I find where two graphs cross on a TI-84?
Press 2nd then TRACE to open CALC, choose 5:intersect, then press ENTER three times: once to accept the first curve, once for the second, and once for the guess.
Is there an official TI-84 emulator I can use online?
Texas Instruments sells TI-SmartView CE, which emulates the TI-84 Plus family on a computer. Free online versions claiming to be a TI-84 generally are not: a genuine emulator needs the calculator ROM, and TI states that distributing the ROM over a network infringes its copyright.