How to Solve Inequalities on TI 84 Calculator

Inequalities are similar to equations, but instead of finding a single value, you are finding a range of values that satisfy a condition. Many students find inequalities confusing, especially when trying to solve them using a calculator.

The TI 84 graphing calculator does not directly solve inequalities like equations, but it provides a powerful way to solve them using graphs. By comparing two functions and analyzing where one is greater than or less than the other, students can identify solution intervals visually.

What You Need Before Starting

Before solving inequalities, make sure your calculator is ready.

TI 84 Calculator Compatibility

This method works for:

TI 84
TI 84 Plus
TI 84 Plus CE

All models support graph-based inequality solving.

Required Calculator Settings

Before starting:

Calculator should be in Function mode
Equations must be entered in the Y= screen
Graph window should clearly display both graphs

Math Prerequisites

You should understand:

Basic inequalities (>, <, ≥, ≤)
Graph interpretation
Coordinate plane concepts

No advanced algebra is required.

How to Use the TI-84 Calculator to Solve Inequalities

The TI 84 solves inequalities by graphing two expressions and comparing their values.

For example:

x² > 4

Can be rewritten as:

y₁ = x²
y₂ = 4

The solution is where the graph of y₁ is above y₂.

Step-by-Step: Solve Inequalities on TI 84

We will solve:

x² > 4

Step 1: Enter Both Functions

Press Y=
Enter X^2 in Y₁
Enter 4 in Y₂
Press ENTER

Step 2: Graph the Functions

Press GRAPH

You will see:

A parabola (y = x²)
A horizontal line (y = 4)

Step 3: Identify Intersection Points

The graphs intersect where:

x² = 4

These points are:

x = -2
x = 2

Step 4: Determine the Solution Region

Look at where:

The parabola is above the line

This occurs when:

x < -2
x > 2

Step 5: Write the Final Answer

The solution is:

x < -2 or x > 2

This can also be written in interval form:

(-∞, -2) ∪ (2, ∞)

Understanding Inequality Graphs

When solving inequalities graphically:

Above a graph means greater than
Below a graph means less than
Intersection points act as boundary values

The TI 84 helps visualize these relationships clearly.

Common Mistakes and How to Fix Them

• Only graphing one equation

Cause: Forgetting to compare two expressions

Fix: Always enter both sides of the inequality

• Misinterpreting graph regions

Cause: Confusion between above and below

Fix: Check which graph is higher

• Graph window hiding intersections

Cause: Incorrect viewing range

Fix: Use Zoom Standard or adjust window settings

Using the Online TI-84 Tool

You can also solve inequalities using the TI 84 Calculator Tool available on this website.

The online tool allows you to:

Graph multiple functions
Compare graph positions
Identify solution intervals
Practice inequality problems easily

Solving inequalities on a TI 84 calculator becomes easier when using graphing techniques. By plotting both sides of the inequality and analyzing where one graph is above or below the other, students can identify solution intervals visually.