1. Reading & Writing Expressions

2. Think…
How would you read these expressions? x (3 +y) (n ÷ 4) + 12 2

3. Objective
I can read and write expressions that record operations with numbers and with letters standing for numbers.

4. Essential Questions What is an algebraic expression?
How do you translate a word problem into an algebraic expression?

5. Variable
Represents an unknown number
Examples: 9 -x y/12 m + 14 2

6. Difference between: Algebraic Expression and Algebraic Equation
An algebraic expression does not have an equals sign y
An algebraic equation has an equals sign y = 52

7. Which of the following is the correct expression?
Writing Expressions
Subtract 23 from x
Which of the following is the correct expression?
23x
23/x
x - 23
23 - x

8. Which of the following is the correct expression?
Writing Expressions
Divide y by 9
Which of the following is the correct expression?
9/y
y/9 9y
y-9

9. Which of the following is the correct expression?
What about this???
Subtract 6 from x then divide by 2
Which of the following is the correct expression?
6x / 2
2 / x-6
x-6+2
x-6 / 2
Break it down

10. Which of the following is the correct expression?
Another Example
Add x to 5 then multiply by 4
Which of the following is the correct expression?
(5x)4
(5 + x)4
(5 + x) / 4
4 / (5 + x)

11. What about this?
Jake bought three pens and a notebook at the store. The notebook cost $4, but the pens didn’t have a price on them. Write an expression that would show how much the total was using (p) as your variable. 3p + $4

12. Another Example
A plumber charges a fee of $40 plus $10 for each hour he works. Write an expression that represents the situation using the variable (h) that determines the cost.
$10h +
$40

13. Another Example
The bike shop charges a flat rate of $15 for renting a bike, plus $3 an hour. Write an expression representing the cost for renting a bike using (h) as your variable.
$3h +
$15

14. Another Example
The pizza shop charges $8 for a large cheese pizza plus $2 for each topping. Write an expression that represents how much it is for a large pizza using (t) as your variable.
$8 + $2t

15. Closure Create your own word problem that involves a variable.
Switch with a partner, and write the expression for their word problem.