Expression Operations

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🎭 The Secret Language of Math: Expression Operations

Once upon a time, in a magical kingdom called Algebra Land, there lived special creatures called “terms.” Let’s discover how they work together!


🧩 What Are Algebraic Expressions?

Imagine you have a recipe box. Each recipe card tells you what ingredients to mix together. An algebraic expression is just like a recipe—it tells you what numbers and letters to combine!

Simple Example:

3x + 5

This means: “Take 3 groups of x, then add 5 more.”

Real Life:

  • Your allowance: $5 per week × number of weeks = 5w
  • Pizza slices: 8 slices minus what you ate = 8 - e

👫 Combining Like Terms: Finding Your Friends!

The Story

Imagine a classroom. Kids with blue shirts sit together. Kids with red shirts sit together. They’re “like” each other!

In math, like terms are terms that have the same variable part.

What Makes Terms “Like”?

Like Terms ✅ Not Like Terms ❌
3x and 5x 3x and 5y
2ab and 7ab 2ab and 7a
4x² and 9x² 4x² and 9x

How to Combine

Just add or subtract the numbers in front!

5x + 3x = 8x

5 apples + 3 apples = 8 apples!

7y - 2y = 5y

7 puppies - 2 puppies = 5 puppies!

Example with multiple terms:

4x + 3y + 2x + 5y
= (4x + 2x) + (3y + 5y)
= 6x + 8y

💡 Pro Tip: Circle like terms with the same color to keep track!


🔢 Evaluating Expressions: Plug and Play!

The Story

Your expression is like a vending machine. You put in a number (the value of x), and it gives you an answer!

How It Works

Expression: 2x + 3

If x = 4:

2(4) + 3
= 8 + 3
= 11

Step-by-Step Process

  1. Write the expression
  2. Replace each variable with its value
  3. Calculate following order of operations

Another Example: Evaluate 3a - b + 2 when a = 5 and b = 4

3(5) - (4) + 2
= 15 - 4 + 2
= 13

🚦 Order of Operations: The Traffic Rules of Math!

The Story

Imagine a busy intersection. Without traffic lights, cars would crash! Math has its own “traffic rules” called the Order of Operations.

The Magic Word: PEMDAS (or BODMAS)

Think of it as: “Please Excuse My Dear Aunt Sally”

Letter Meaning Example
P Parentheses (2 + 3) first!
E Exponents 2² = 4
M/D Multiply/Divide Left to right
A/S Add/Subtract Left to right

Watch It in Action

Problem: 3 + 4 × 2

Wrong way: 3 + 4 = 7, then 7 × 2 = 14

Right way: 4 × 2 = 8 first, then 3 + 8 = 11

Another Example: (5 + 3) × 2 - 4

Step 1: (5 + 3) = 8     ← Parentheses first
Step 2: 8 × 2 = 16      ← Multiply
Step 3: 16 - 4 = 12     ← Subtract
graph TD A[Start with expression] --> B{Parentheses?} B -->|Yes| C[Solve inside first] B -->|No| D{Exponents?} C --> D D -->|Yes| E[Calculate powers] D -->|No| F{× or ÷?} E --> F F -->|Yes| G[Left to right] F -->|No| H{+ or -?} G --> H H -->|Yes| I[Left to right] I --> J[Done!]

✨ Simplifying Expressions: Clean Up Time!

The Story

Your room is messy with toys everywhere. Simplifying is like putting all the same toys in the same box!

What “Simplify” Means

Make the expression shorter and cleaner without changing its value.

The Process

  1. Remove parentheses (distribute if needed)
  2. Combine like terms
  3. Write in standard form (highest power first)

Example: Simplify 3x + 2 + 5x - 7

Step 1: Group like terms
        (3x + 5x) + (2 - 7)
Step 2: Combine
        8x + (-5)
Step 3: Clean up
        8x - 5

Another Example: Simplify 2(x + 3) + 4x

Step 1: Distribute the 2
        2x + 6 + 4x
Step 2: Combine like terms
        6x + 6

➕ Adding Expressions: The Party!

The Story

Two groups of friends are joining the same party. You just count how many of each type of friend you have now!

How to Add

Just remove the parentheses and combine like terms!

Example: Add (3x + 2) and (5x + 4)

(3x + 2) + (5x + 4)
= 3x + 2 + 5x + 4
= 8x + 6

Another Example: (2a + 3b) + (4a - b)

= 2a + 3b + 4a - b
= 6a + 2b

💡 Remember: Adding is the easy one—signs stay the same!


➖ Subtracting Expressions: The Opposite Game!

The Story

When you subtract, it’s like playing the “opposite game.” Everything in the second group becomes its opposite!

The Secret Rule

Subtracting is the same as adding the opposite!

When you see a minus sign before parentheses, flip all the signs inside.

Example: Subtract (3x + 4) from (7x + 2)

(7x + 2) - (3x + 4)
= 7x + 2 - 3x - 4    ← Signs flipped!
= 4x - 2

Watch the Signs Carefully!

(5a - 2b) - (2a + 3b)
= 5a - 2b - 2a - 3b   ← +3b becomes -3b
= 3a - 5b
graph TD A[Second expression] --> B[Flip + to -] A --> C[Flip - to +] B --> D[Now add normally] C --> D

✖️ Multiplying Expressions: The Distribution Power!

The Story

Imagine you’re handing out party favors. Everyone at the party gets everything in the bag. That’s distribution!

Multiplying a Number by an Expression

Every term inside gets multiplied!

Example: 3(2x + 4)

= 3 × 2x + 3 × 4
= 6x + 12

Multiplying Two Expressions (FOIL)

Use FOIL: First, Outer, Inner, Last

Example: (x + 2)(x + 3)

F: x × x = x²
O: x × 3 = 3x
I: 2 × x = 2x
L: 2 × 3 = 6

= x² + 3x + 2x + 6
= x² + 5x + 6

Visual Guide

    (x + 2)(x + 3)
     ↓   ↓  ↓   ↓
     F   I  O   L

Another Example: (2x + 1)(x - 4)

F: 2x × x = 2x²
O: 2x × (-4) = -8x
I: 1 × x = x
L: 1 × (-4) = -4

= 2x² - 8x + x - 4
= 2x² - 7x - 4

➗ Dividing Expressions: Fair Sharing!

The Story

You have a bag of candies to share fairly among friends. Each friend gets the same portion of each type!

Dividing by a Number

Divide each term by the number!

Example: (6x + 12) ÷ 2

= 6x ÷ 2 + 12 ÷ 2
= 3x + 6

Dividing by a Variable

Example: (8x² + 4x) ÷ 2x

= 8x² ÷ 2x + 4x ÷ 2x
= 4x + 2

Simple Rule

When dividing variables:

  • Subtract the exponents
  • x³ ÷ x = x²
  • x² ÷ x² = 1

Another Example: (15a²b + 10ab) ÷ 5a

= 15a²b ÷ 5a + 10ab ÷ 5a
= 3ab + 2b

🎯 Quick Reference Chart

Operation Key Rule Example
Combine Same variables only 3x + 5x = 8x
Evaluate Substitute values 2x + 1, x=3 → 7
Order PEMDAS 2 + 3 × 4 = 14
Simplify Combine all like terms 2x + 3 + x = 3x + 3
Add Remove ( ), combine (2x)+(3x) = 5x
Subtract Flip signs, combine (5x)-(2x) = 3x
Multiply Distribute (FOIL) 2(x+3) = 2x+6
Divide Divide each term (6x+4)÷2 = 3x+2

🌟 You Did It!

You’ve just learned the building blocks of algebra! These operations are like learning the alphabet—once you know them, you can “read” and “write” in the language of mathematics.

Remember:

  • Like terms are friends who can combine
  • PEMDAS keeps your math in order
  • Signs flip when you subtract expressions
  • Every term gets multiplied or divided

Now go practice and become an expression master! 🚀

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