What Are Variable Expressions?
Variables are like mystery numbers!
In math, we sometimes use letters (like x, y, or z) to stand for numbers we don't know yet.
Evaluating an expression means figuring out what the expression equals when we know what number the variable represents.
How To Evaluate Expressions
1️⃣ Substitute - Replace the variable with the number it represents
2️⃣ Calculate - Do the math operations in order (PEMDAS)
3️⃣ Simplify - Write your final answer neatly
Let's Try Some Examples!
Example 1
Evaluate 3x + 5 when x = 4
1. Substitute: 3(4) + 5
2. Calculate: 12 + 5 = 17
3. Answer: 17
Example 2
Evaluate 2y² - 10 when y = 3
1. Substitute: 2(3)² - 10
2. Calculate exponents first: 2×9 - 10
3. Then multiply: 18 - 10 = 8
4. Answer: 8
Parent Tips 🌟
- Make it real: Use real-life examples like "If you get x cookies and your friend gives you 3 more, how many do you have when x=5?"
- Visual aids help: Draw boxes or use objects to represent variables before substituting numbers.
- Celebrate mistakes: Wrong answers are great learning opportunities - ask your child to explain their steps to find where things went wrong.