Learn on PengiSaxon Math, Course 3Chapter 7: Algebra

Lesson 62: Graphing Solutions to Inequalities on a Number Line

In this Grade 8 lesson from Saxon Math, Course 3, students learn how to write and solve inequalities, then graph their solution sets on a number line using open and closed circles to indicate excluded and included values. The lesson covers translating word problems into inequality notation, solving multi-step inequalities such as 3x + 1 ≤ 7 by applying inverse operations, and representing continuous solution sets with shaded regions and arrows. Students also practice verifying their solution sets by testing values inside and outside the graphed region.

Section 1

📘 Graphing Solutions to Inequalities on a Number Line

New Concept

An inequality is a mathematical statement used to indicate a range of possible numbers. Letting xx represent a possible number, we write

1<x<101 < x < 10
We read this as "xx is greater than 1 and less than 10."

What’s next

This card just sets the stage. Next, you’ll work through examples on solving inequalities and graphing their solutions on a number line.

Section 2

Graphing inequalities on a number line

Property

An inequality shows a range of possible values. Use an open circle to show a number is excluded (like with << or >>) and a solid, filled-in circle to show a number is included (like with \le or \ge). The shaded part of the number line represents the entire solution set of possible numbers.

Examples

  • To graph x>3x > 3, place an open circle on 3 and shade the number line to the right.
  • To graph x2x \le -2, place a solid circle on -2 and shade the number line to the left.
  • To graph 1<x51 < x \le 5, place an open circle on 1, a solid circle on 5, and shade between them.

Explanation

Think of it as a VIP party guest list! An open circle means that number didn't get an invite, but all the numbers nearby did. A solid circle means that number is the guest of honor and is definitely included! The shaded line is the dance floor where all the cool, invited numbers hang out.

Section 3

Solving Two-Step Inequalities

Property

Solve an inequality just like an equation by using inverse operations to isolate the variable. Whatever you do to one side, you must do to the other to keep it balanced. For example, to solve 3x+173x + 1 \le 7, you first subtract 1 from both sides, then divide both sides by 3.

Examples

  • 4x+3114x8x24x + 3 \le 11 \rightarrow 4x \le 8 \rightarrow x \le 2
  • 2y5>92y>14y>72y - 5 > 9 \rightarrow 2y > 14 \rightarrow y > 7
  • 8x311x8 \le x - 3 \rightarrow 11 \le x, which is the same as x11x \ge 11

Explanation

Solving an inequality is like being a secret agent on a mission to isolate the variable 'x'! First, you have to get rid of any sidekicks hanging around by adding or subtracting. Then, if 'x' has a coefficient partner, you divide to uncover its true identity. Just follow the steps to crack the code!

Book overview

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Continue this chapter

Chapter 7: Algebra

  1. Lesson 1

    Lesson 61: Sequences

  2. Lesson 2Current

    Lesson 62: Graphing Solutions to Inequalities on a Number Line

  3. Lesson 3

    Lesson 63: Rational Numbers, Non-Terminating Decimals, and Percents and Fractions with Negative Exponents

  4. Lesson 4

    Lesson 64: Using a Unit Multiplier to Convert a Rate

  5. Lesson 5

    Lesson 65: Applications Using Similar Triangles

  6. Lesson 6

    Lesson 66: Special Right Triangles

  7. Lesson 7

    Lesson 67: Percent of Change

  8. Lesson 8

    Lesson 68: Probability Multiplication Rule

  9. Lesson 9

    Lesson 69: Direct Variation

  10. Lesson 10

    Lesson 70: Solving Direct Variation Problems

  11. Lesson 11

    Investigation 7: Probability Simulation

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

📘 Graphing Solutions to Inequalities on a Number Line

New Concept

An inequality is a mathematical statement used to indicate a range of possible numbers. Letting xx represent a possible number, we write

1<x<101 < x < 10
We read this as "xx is greater than 1 and less than 10."

What’s next

This card just sets the stage. Next, you’ll work through examples on solving inequalities and graphing their solutions on a number line.

Section 2

Graphing inequalities on a number line

Property

An inequality shows a range of possible values. Use an open circle to show a number is excluded (like with << or >>) and a solid, filled-in circle to show a number is included (like with \le or \ge). The shaded part of the number line represents the entire solution set of possible numbers.

Examples

  • To graph x>3x > 3, place an open circle on 3 and shade the number line to the right.
  • To graph x2x \le -2, place a solid circle on -2 and shade the number line to the left.
  • To graph 1<x51 < x \le 5, place an open circle on 1, a solid circle on 5, and shade between them.

Explanation

Think of it as a VIP party guest list! An open circle means that number didn't get an invite, but all the numbers nearby did. A solid circle means that number is the guest of honor and is definitely included! The shaded line is the dance floor where all the cool, invited numbers hang out.

Section 3

Solving Two-Step Inequalities

Property

Solve an inequality just like an equation by using inverse operations to isolate the variable. Whatever you do to one side, you must do to the other to keep it balanced. For example, to solve 3x+173x + 1 \le 7, you first subtract 1 from both sides, then divide both sides by 3.

Examples

  • 4x+3114x8x24x + 3 \le 11 \rightarrow 4x \le 8 \rightarrow x \le 2
  • 2y5>92y>14y>72y - 5 > 9 \rightarrow 2y > 14 \rightarrow y > 7
  • 8x311x8 \le x - 3 \rightarrow 11 \le x, which is the same as x11x \ge 11

Explanation

Solving an inequality is like being a secret agent on a mission to isolate the variable 'x'! First, you have to get rid of any sidekicks hanging around by adding or subtracting. Then, if 'x' has a coefficient partner, you divide to uncover its true identity. Just follow the steps to crack the code!

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 7: Algebra

  1. Lesson 1

    Lesson 61: Sequences

  2. Lesson 2Current

    Lesson 62: Graphing Solutions to Inequalities on a Number Line

  3. Lesson 3

    Lesson 63: Rational Numbers, Non-Terminating Decimals, and Percents and Fractions with Negative Exponents

  4. Lesson 4

    Lesson 64: Using a Unit Multiplier to Convert a Rate

  5. Lesson 5

    Lesson 65: Applications Using Similar Triangles

  6. Lesson 6

    Lesson 66: Special Right Triangles

  7. Lesson 7

    Lesson 67: Percent of Change

  8. Lesson 8

    Lesson 68: Probability Multiplication Rule

  9. Lesson 9

    Lesson 69: Direct Variation

  10. Lesson 10

    Lesson 70: Solving Direct Variation Problems

  11. Lesson 11

    Investigation 7: Probability Simulation