MathIsimple
Back to Unit 3

Lesson 3-1: Simplifying Algebraic Expressions

Scenario: Phone Plans - Learn to simplify algebraic expressions by comparing phone plan costs!

Duration: 55-70 minutesScenario: Phone Plans

Learning Objectives

  • Apply the distributive property to expand expressions
  • Combine like terms to simplify expressions
  • Compare costs using simplified expressions
  • Interpret the meaning of simplified expressions

Phone Plan Comparison Scenario

The Problem

Compare two phone plans:

  • Plan A: $50 base fee + $0.10 per minute
  • Plan B: $30 base fee + $0.20 per minute

Let x = number of minutes used. Find the difference in cost between the plans.

Cost expressions:
Plan A: 50 + 0.1x
Plan B: 30 + 0.2x
Difference: (50 + 0.1x) - (30 + 0.2x)

Simplifying the Expression

Step 1: Remove parentheses using distributive property

(50 + 0.1x) - (30 + 0.2x) = 50 + 0.1x - 30 - 0.2x

Step 2: Combine like terms

50 + 0.1x - 30 - 0.2x = (50 - 30) + (0.1x - 0.2x) = 20 - 0.1x

Final simplified expression: 20 - 0.1x

Distributive Property

The Rule

Distributive Property: a(b + c) = ab + ac

We can "distribute" multiplication over addition or subtraction.

Examples

Example 1

3(2x + 5) = 3 × 2x + 3 × 5 = 6x + 15

Example 2

4(x - 3) = 4 × x - 4 × 3 = 4x - 12

Combining Like Terms

What are Like Terms?

Like Terms: Terms that have the same variable raised to the same power.

Examples: 3x and 5x are like terms; 2x² and 7x² are like terms; but 3x and 2x² are NOT like terms.

Practice Example

Simplify: 3(2x - 5) + 4x

Step 1: Apply distributive property

3(2x - 5) + 4x = 6x - 15 + 4x

Step 2: Combine like terms

6x - 15 + 4x = (6x + 4x) - 15 = 10x - 15

Practice Problems

Problem 1: Distributive Property

Simplify: 5(3x + 2)

Your solution:

Problem 2: Combining Like Terms

Simplify: 2x + 5 - 3x + 7

Your solution:

Problem 3: Complex Expression

Simplify: 4(2x - 3) + 2(x + 1)

Your calculation: