Learn on PengiBig Ideas Math, Course 3Chapter 1: Equations

Lesson 3: Solving Equations with Variables on Both Sides

In this Grade 8 lesson from Big Ideas Math, Course 3 (Chapter 1: Equations), students learn to solve equations with variables on both sides by collecting variable terms on one side and constant terms on the other using the Addition, Subtraction, and Division Properties of Equality. The lesson also covers applying the Distributive Property to multi-step equations and determining whether an equation has one solution, no solution, or infinitely many solutions. Real-world contexts like perimeter, area, surface area, and volume are used to build and solve these equations.

Section 1

Solving Equations with Variables on Both Sides

Property

Step 1. Simplify each side of the equation as much as possible.

  • Use the Distributive Property to remove any parentheses.
  • Combine like terms.

Step 2. Collect all the variable terms on one side of the equation.

  • Use the Addition or Subtraction Property of Equality.

Step 3. Collect all the constant terms on the other side of the equation.

  • Use the Addition or Subtraction Property of Equality.

Step 4. Make the coefficient of the variable term to equal to 1.

  • Use the Multiplication or Division Property of Equality.
  • State the solution to the equation.

Step 5. Check the solution.

  • Substitute the solution into the original equation to make sure the result is a true statement.

Examples

Section 2

Equations with no solution

Property

If solving an equation with variables on both sides results in a false statement, such as 0=100 = -10 or 3=73 = 7, then the equation has no solution.

Examples

Section 3

Equations with Infinitely Many Solutions

Property

An equation has infinitely many solutions when algebraic manipulation results in a true statement where both sides are identical, such as a=aa = a where aa is any real number.

Examples

Book overview

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

Continue this chapter

Chapter 1: Equations

  1. Lesson 1

    Lesson 1: Solving Simple Equations

  2. Lesson 2

    Lesson 2: Solving Multi-Step Equations

  3. Lesson 3Current

    Lesson 3: Solving Equations with Variables on Both Sides

  4. Lesson 4

    Lesson 4: Rewriting Equations and Formulas

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Solving Equations with Variables on Both Sides

Property

Step 1. Simplify each side of the equation as much as possible.

  • Use the Distributive Property to remove any parentheses.
  • Combine like terms.

Step 2. Collect all the variable terms on one side of the equation.

  • Use the Addition or Subtraction Property of Equality.

Step 3. Collect all the constant terms on the other side of the equation.

  • Use the Addition or Subtraction Property of Equality.

Step 4. Make the coefficient of the variable term to equal to 1.

  • Use the Multiplication or Division Property of Equality.
  • State the solution to the equation.

Step 5. Check the solution.

  • Substitute the solution into the original equation to make sure the result is a true statement.

Examples

Section 2

Equations with no solution

Property

If solving an equation with variables on both sides results in a false statement, such as 0=100 = -10 or 3=73 = 7, then the equation has no solution.

Examples

Section 3

Equations with Infinitely Many Solutions

Property

An equation has infinitely many solutions when algebraic manipulation results in a true statement where both sides are identical, such as a=aa = a where aa is any real number.

Examples

Book overview

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

Continue this chapter

Chapter 1: Equations

  1. Lesson 1

    Lesson 1: Solving Simple Equations

  2. Lesson 2

    Lesson 2: Solving Multi-Step Equations

  3. Lesson 3Current

    Lesson 3: Solving Equations with Variables on Both Sides

  4. Lesson 4

    Lesson 4: Rewriting Equations and Formulas