Writing Expressions

1. Writing Expressions

2. Steps to writing a verbal expression: • Write a model of the situation using words. • Define a variable. • Write an algebraic expression. What does it mean to define a variable? - You do this when you choose a variable to represent an unknown number.

3. Common Words/Phrases that indicate the operation in the expression *LOOK FOR THESE WORDS TO HELP YOU DETERMINE THE OPERATION

4. Example 1 – Write an Algebraic Expression • Marcia is 5 years older than her brother. What don’t we know? Her brother’s age. We will use n to represent her brother’s age. Five Years older than her brother’s age 5 + n We represent this as 5 + n.

5. Example 2 – Write an Algebraic Expression • Anna makes nine dollars an hour. What don’t we know? How many hours she works. We will use n to represent the number of hours. Nine dollars hour an 9 ∙ n We represent this as 9 ∙ n or 9n.

6. Example 3 – Write an Algebraic Expression • For the magic trick, the number I chose is ten less than the number the magician chose. What don’t we know? The number the magician chose. We will use n to represent the magician’s number. Ten less than magician’s number 10 - n LESS THAN IS A SWITCH PHRASE. This means you switch the order of the phrase We represent this as n – 10.

7. Now your turn! • The difference between seven and a number. • The quotient of a number and nine. • A four dollar tip is added to the bill. • The product of twelve and a number. • We scored 5 points less than the other team. 7 - n n ÷ 9 4 + n 12n n - 5