Posted on April 25, 2022 (Updated on July 26, 2025)

How do you graph inequalities on a TI 84 Plus?

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Taming Inequalities on Your TI-84 Plus: A Human’s Guide

So, you’re staring at an inequality and your TI-84 Plus, wondering how to make them play nice? You’re not alone! These calculators are workhorses, but graphing inequalities isn’t exactly their forte. Don’t worry, though; with a few tricks, you can absolutely visualize those inequalities and conquer your math homework.

Forget directly typing in those fancy inequality symbols. The TI-84 Plus doesn’t roll that way. Instead, we’ll use some clever workarounds to shade the areas we need. Let’s dive in!

Method 1: Shading the Way to Success (Two-Variable Inequalities)

This is your go-to method for inequalities like y > x + 1 or y ≤ -2x + 5. We’re going to trick the calculator into shading the right region.

Here’s the lowdown:

  • Hit that Y= button: This is where the magic happens. It’s where you tell the calculator what equations you want to see.
  • Type in the equation: Pretend it’s a regular y = equation. So, for y ≤ 3x + 2, just enter 3X + 2 into Y1. Easy peasy.
  • Get Stylin’ with Graph Styles: This is the key!
    • Use the left arrow ◄ to go all the way to the left of Y1. See that little symbol flashing? That’s what we’re messing with.
    • Smash the ENTER button repeatedly. Watch how that symbol changes! We’re cycling through different graph styles.
    • For y < or y ≤: Find the style with a little triangle pointing downwards. That tells the calculator to shade below the line. Think of it like “less than” means “down low.”
    • For y > or y ≥: Snag the style with the triangle pointing upwards. Shade above the line!
  • GRAPH It! Hit that graph button and BAM! The calculator draws the line and shades the area that makes the inequality true.

    • Decoding the Graph:

    • A solid line? That means the line is part of the answer (for ≤ or ≥). But here’s a gotcha: the TI-84 can’t draw dotted lines. So, if you have a strict inequality (< or >), remember that the line itself isn’t included. Make a mental note!
    • The shaded area? That’s where all the (x, y) pairs live that make the inequality happy. Every point in that area is a solution.

    Method 2: Number Line Ninja (One-Variable Inequalities)

    Okay, so the TI-84 isn’t really designed for number lines, but we can MacGyver it! This is for inequalities like x > 3 or x ≤ -1.

    Let’s do this:

  • Back to the Y= screen: You know the drill.
  • Type in the Inequality: This time, we do use the inequality symbols! Hit 2ndMATH (that’s the TEST menu) to find them. For x > 3, enter X > 3.
  • ZOOM6 for Standard View: This gives you a decent window to see what’s going on.

    • What You’ll See:

    • A horizontal line. Yep, it’s a bit weird. The calculator draws a line at y = 1 where the inequality is true, and y = 0 where it’s false.
    • Think of the x-axis as your number line. The line shows you where the inequality holds up.

    Method 3: Unleash the “Inequalz” App (TI-84 Plus CE Only)

    Got a TI-84 Plus CE? You’re in luck! It has a built-in app called “Inequalz” that makes graphing inequalities way easier.

    Here’s the scoop:

  • APPS Button Time: Press it. Find “Inequalz” in the list.
  • Hit ENTER: If it’s the first time, it might ask you to press any key. Do it.
  • Inequality Editor: The Y= screen pops up, but now you’ve got inequality symbols at the bottom! Highlight the equal sign and press the ALPHA key along with the corresponding function key (F1-F5) to select the inequality symbol.
  • Graph Away! Type in your expressions and hit GRAPH. The app shades everything for you, automatically!

    • Why the App Rocks:

    • No More Tricks: You can type inequality symbols directly. Hallelujah!
    • Auto-Shading: It just works.
    • Intersection Power: Graph multiple inequalities and it’ll highlight where they overlap (the “feasible region”). Super useful for solving systems of inequalities.
    • Trace Those Points: It can even help you find the exact points where the lines intersect.

    Pro Tips and Gotchas

    • App Conflicts: Sometimes other apps (like “Transforms”) can mess with the inequality graphing. If things get wonky, quit the other apps.
    • Window, Window: Make sure your WINDOW settings (Xmin, Xmax, Ymin, Ymax) are set so you can actually see the graph! ZOOM6 (ZStandard) is your friend.
    • ShadeRes: In the app, “ShadeRes” controls how solid the shading looks. Lower numbers = darker shading.
    • Test Mode: Some tests ban apps. Know the rules!
    • Battery Blues: Keep those AAA batteries away from kids! They’re a choking hazard.

    Graphing inequalities on a TI-84 Plus can feel a bit clunky at first, but with these methods, you’ll be visualizing solutions like a pro. So go forth, conquer those inequalities, and ace that math test!

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