Unit 4 · Topic 2

Inequalities & Number Lines

Overview

Solve like equations, then graph every value that works.

Topic 2 of 3~46 min
Unit overview

The lesson

This lesson teaches Inequalities & Number Lines. Read each section in order, work through every example on paper, then use the practice problems and quick check at the bottom.

Reading inequality symbols

An inequality compares values that are not necessarily equal: < (less than), > (greater than), ≤ (at most), ≥ (at least). "At most 9" means x ≤ 9; "fewer than 5" means x < 5.

When you study reading inequality symbols, slow down and write one example in your notebook without looking at the screen. That active step is what turns reading into learning.

Solving and graphing

Solve an inequality the same way you solve an equation. Then graph the solution on a number line: an open circle for < or >, a closed (filled) circle for ≤ or ≥.

An equation says two expressions have the same value. Whatever you do to one side, you must do to the other to keep the balance.

Check your solution by substituting it back into the original equation. If both sides match, your answer is correct.

Worked example

Solve and graph x + 3 < 10

  1. 1Subtract 3 from both sides: x < 7.
  2. 2Graph an open circle at 7 and shade everything to the left.

Why this matters

Inequalities & Number Lines shows up constantly in solve like equations, then graph every value that works. It also connects to what you will see on homework, quizzes, and the next unit in this grade.

Teachers often move fast in class. This page is here so you can pause, re-read, and practice until the idea feels familiar, not just until you have memorized a rule for one day.

Common mistakes to avoid

Rushing to the answer without writing steps. Middle-school math rewards clear work, and you catch errors earlier when steps are visible.

Mixing up similar ideas from the same topic. If two terms feel alike, make a two-column note: what is the same, what is different, and one example of each.

Key ideas from this lesson

  1. Reading inequality symbols
  2. Solving and graphing

Video walkthrough

Khan Academy

Intro to Inequalities

Symbols like < and ≥ and what they mean on a number line.

Watch on YouTube
Math Antics

Solving Inequalities

Solve inequality problems the same way you solve equations.

Watch on YouTube

Practice

For each problem: write your work in the box, type your answer, and check it. If you are stuck, reveal the solution one step at a time. Do not skip straight to the final answer.

Exercise 1

Try it yourself

Solve: x + 4 > 11. Write the solution as an inequality.

Step-by-step solution

  1. 1Subtract 4 from both sides.
  2. 2x > 7.

Exercise 2

Try it yourself

Which inequality means "x is at least 12"?

Step-by-step solution

  1. 1"At least" includes 12 and all greater values.
  2. 2That is x ≥ 12.

Exercise 3

Try it yourself

Solve: 3n ≤ 18.

Step-by-step solution

  1. 1Divide both sides by 3.
  2. 2n ≤ 6.

Exercise 4

Try it yourself

You must be at least 48 inches tall to ride. Write an inequality for height h.

Step-by-step solution

  1. 1Height must be 48 or more.
  2. 2h ≥ 48.

Exercise 5

Try it yourself

Solve: 2x − 5 < 13.

Step-by-step solution

  1. 1Add 5 to both sides: 2x < 18.
  2. 2Divide by 2: x < 9.

Quick check

Answer all questions. Retake the quiz until you feel confident before moving on.

Inequalities & Number Lines

Question 1 of 5

Medium

Which inequality represents 'x is at most 9'?

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