Writing Algebraic Expressions
Writing Algebraic Expressions
Introduction: Write the following expression: five plus two. Chances are you were able to turn this phrase into 5+2. In algebra, you will be asked to do the same. However, one or more of the terms will have an unknown quantity. To write the unknown, you will need to use a variable. A variable is a symbol, usually a letter, which represents an unknown value.
Write the following expression: five plus a number. Begin by turning each part of the expression into its mathematical form:
- five →5
- plus →+
- a number →n (use any letter)
Then, combine the terms into the expression 5+n. Congratulations, you just wrote an algebraic expression!
Remember, expressions do not include an equal sign (=). Learning the words and phrases that indicate each math operation will help you when writing expressions. See the table below for examples.
| Addition | Subtraction | Multiplication | Division | Variable |
|---|---|---|---|---|
| add sum increase more than plus combined | subtract minus difference decrease fewer less* less than* | multiply product times of twice double triple | divide quotient per fraction part | a number some number unknown x or any letter |
*Less and less than are not the same!
- two less a number →2-x
- two less than a number →x-2
Directions for This Lesson: In this lesson, you will be learn how to write algebraic expressions. First, try the practice questions to determine what you already know. Then, watch the video lessons to learn more.
Required Videos:
Practice:
Practice what you have learned by completing the post-lesson worksheet.
Related Worksheets:
Additional Resources: