To graph on a TI-84, press Y=, type the function next to Y1 using the X,T,θ,n key for x, and press GRAPH. If nothing shows up, press ZOOM and then 6 for ZStandard to reset the window to −10 through 10. The grapher above works the same way and runs in your browser.
How to graph on a TI-84
Every graph starts in the Y= editor. This page is the hub for graphing on the site, and the same steps work in the full simulator on the free TI-84 calculator online.
- Press Y=.
- Press CLEAR to erase any old function next to Y1.
- Type the function. Press X,T,θ,n for x, and use ^ or x² for powers.
- Press ENTER to move to Y2 if you want a second function.
- Press GRAPH.
- Press TRACE and use the left and right arrows to read points on the curve.
Here, type x^2 or X^2 for x squared. Lowercase and uppercase both work, and 2x means 2 times x, just like on the handheld.
Fixing a blank graph
A blank graph almost always comes from the window. If your function lives at y = 500 and the window only shows −10 to 10, the curve is off the screen.
- Press ZOOM, then 6 for ZStandard to return to −10 through 10 on both axes.
- Press ZOOM, then 0 for ZoomFit to stretch the y range around your function.
- Check that the = sign next to Y1 is highlighted. A plain = sign means the function is turned off.
- Press WINDOW and make sure Xmin is less than Xmax and Ymin is less than Ymax.
If you see ERR:INVALID DIM instead, a stat plot is on with an empty list. Turn the plots off as described in the FAQ below, or look up any other message in the TI-84 error codes table.
ZOOM menu explained
The ZOOM menu changes the window for you. These are the options on a TI-84 Plus CE.
| Key | Option | What it does |
|---|---|---|
| 1 | ZBox | Draw a box to zoom into |
| 2 | Zoom In | Zoom in around the cursor |
| 3 | Zoom Out | Zoom out around the cursor |
| 4 | ZDecimal | Trace moves in steps of .1 |
| 5 | ZSquare | Equal units on both axes, so circles look round |
| 6 | ZStandard | Resets to −10 through 10 on both axes |
| 7 | ZTrig | Fits trig graphs with π/2 tick marks |
| 8 | ZInteger | Trace moves in whole number steps |
| 9 | ZoomStat | Fits the window to your stat plot data |
| 0 | ZoomFit | Keeps x, adjusts y to fit the function |
Finding intersections
The intersect tool finds where two graphs cross. Both functions need to be on and visible in the window.
- Graph both functions, for example Y1 and Y2.
- Press 2nd TRACE, then 5 for intersect.
- At First curve?, press ENTER.
- At Second curve?, press ENTER.
- At Guess?, move the cursor near the crossing and press ENTER.
The TI-84 finds one crossing per run, the one closest to your guess. Run it again with a new guess to find the next one. The Intersections button above lists every crossing in the window at once.
Worked example
Graph Y1 = X² − 4 and Y2 = 2X + 1 in the standard window. The parabola crosses the x-axis at −2 and 2, and its lowest point is the vertex at (0, −4).
To find where they meet, set X² − 4 = 2X + 1, which becomes X² − 2X − 5 = 0. The quadratic formula calculator gives X = 1 ± √6.
| Point | X | Y |
|---|---|---|
| First intersection | −1.449489743 | −1.898979486 |
| Second intersection | 3.449489743 | 7.898979486 |
| Minimum of Y1 | 0 | −4 |
Press Intersections above and the same two points appear, marked on the graph. On a handheld you would run 2nd TRACE, 5 twice, once with a guess near each crossing.
Common mistakes
- Typing a negative with the subtraction key. On the handheld, use (−) for −X or −3.
- Writing 1/2X and expecting 1 over 2X. The TI-84 reads it as (1/2)X, so type 1/(2X) instead.
- Graphing trig in the wrong angle mode. Use RADIAN for most graphs, or the curve looks flat.
- Guessing too far from the crossing in intersect, which returns a different crossing than you wanted.
FAQ
Why is my TI-84 graph blank?
Usually the window does not include the part of the graph you need. Press ZOOM then 6 for ZStandard, or ZOOM then 0 for ZoomFit. Also check that the = sign next to your function is highlighted, since a function that is turned off will not draw at all.
How do you reset the graphing window on a TI-84?
Press ZOOM, then 6 for ZStandard. The window snaps back to Xmin −10, Xmax 10, Ymin −10, and Ymax 10, with a scale of 1 on both axes. The graph redraws right away. To set custom values instead, press WINDOW and type each one.
How do you find where two graphs intersect on a TI-84?
Graph both functions, then press 2nd TRACE and 5 for intersect. Press ENTER at First curve? and again at Second curve?. Move the cursor close to the crossing and press ENTER at Guess?. The screen shows the X and Y values of that intersection.
What does ZStandard do?
ZStandard resets the graphing window to the default view. Both axes run from −10 to 10 with a tick mark at every unit. It is item 6 in the ZOOM menu, and it is the fastest fix when a graph looks empty, stretched, or too far zoomed in.
How do you turn off a plot on a TI-84?
Press 2nd Y= to open STAT PLOT, choose 4 for PlotsOff, and press ENTER. All three plots turn off at once. You can also go to the Y= screen, move the cursor up to the highlighted Plot1 at the top, and press ENTER to switch it off.
How many equations can a TI-84 graph at once?
Ten in function mode, labeled Y1 through Y9 and Y0. Each one can be turned on or off from the Y= screen by highlighting its = sign. This grapher works the same way, with ten rows and a switch beside each one.