Deriving and Evaluating Expressions with One Variable
Learn what expressions with one variable are, like , and how to derive and evaluate them. Let’s get started! 🚀
Video Lesson
Watch and learn the basics
Flashcards
Review key concepts visually
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🛎️ Understanding Variables
- A variable is a letter that stands for a number that can change.
- For example, x can represent the number of months passed.
🛎️ Understanding Expressions
- An expression is formed by combining numbers and variables.
- It shows how a value changes and has no equals sign.
🛎️ Forming Expressions
- Example 1: 20 + 5x means start with 20 and add 5 for each x.
- Example 2: 50 − 3y means start with 50 and subtract 3 for each y.
🛎️ Evaluating Expressions
- To evaluate an expression, you replace the variable with a number.
- You then calculate to find the value of the expression.
Practice Questions
Test your understanding
Julia has £20 in savings. Each month, she saves an additional £5. How much will she have saved after 5 months?
Correct! 🎉 +10 pointsNot quite right
The expression is . After 5 months, Julia will have (£).
A library has 200 books. Every week, 10 new books are added. How many books will the library have after 3 weeks?
Correct! 🎉 +10 pointsNot quite right
The expression is . After 3 weeks, the library will have books.
You start with £100, and you spend £8 each day. How much money will you have left after 12 days?
Correct! 🎉 +20 pointsNot quite right
The expression is . After 12 days, you'll have (£) left.
A factory starts with 1000 units of a product. They produce 125 units every day. After how many days will they have a total of 2000 units?
Correct! 🎉 +20 pointsNot quite right
The equation is . Solving for , we get days.
A gardener plants 15 flowers each day. They start with 50 flowers already planted. How many flowers will they have after 7 days?
Correct! 🎉 +20 pointsNot quite right
The expression is . After 7 days, the gardener will have flowers in total.
A photographer charges £50 for a session. They charge an additional £30 for each extra photo. How much will the photographer charge after 12 photos?
Correct! 🎉 +30 pointsNot quite right
The expression is . After 12 photos, , so the photographer will charge (£).
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Interactive Activity
Build and evaluate expressions with one variable
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