Unit 33: Systems of Linear Equations

Day 15 of 30

Elimination: subtracting equations

6-8Mathematics

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Learning Objective

Students will solve elimination and subtracting equations through guided practice and application.

Today's Lesson

In this lesson, we'll explore elimination: subtracting equations. Mathematical thinking develops logical reasoning and problem-solving abilities.

Subtraction means taking away from a group to find how many are left. When we see 5 - 2, we start with 5 objects and take away 2. We can count what's left: 3 objects remain. So 5 - 2 = 3. The "-" symbol means "minus" or "subtract." Subtraction is the opposite of addition!

As you work through today's material, pay attention to the examples and try to identify the patterns or strategies being used. This will help you apply these concepts to new problems.

Take notes on key points and make connections to what you've already learned in previous lessons.

Key Terms
Problem

A mathematical question requiring analysis and solution

Solution

The result obtained by solving a problem

Activities
Instructions
1. Review the example problems for elimination: subtracting equations. 2. Identify the steps and strategies used. 3. Work through practice problems independently. 4. Compare solutions with a partner.
Materials Needed
  • Notebook
  • Calculator (if needed)
  • Graph paper
Practice Problems
1

Solve for x: x + 7 = 15

Hint: Subtract 7 from both sides.
2

Solve for y: 3y = 12

Hint: Divide both sides by 3.
3

If 2x - 5 = 9, what is x?

Hint: Add 5 to both sides, then divide by 2.

Teaching Tip

For advanced learners: Encourage deeper analysis and real-world connections. Consider extension activities that allow students to apply elimination: subtracting equations to novel situations.

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