1. Evaluating and Writing Expressions

2. What is an Algebraic Expression?
An algebraic expression contains at least one variable and at least one operation.
Example: 2 + a 4x
c- 5
y/5

3. What is a Variable? A variable is a letter that stands for a number.
**ANY letter can be used as a variable.**
*The letter x is most often used.
Example: a x y

4. What is a Variable?
To avoid confusion with the “x” (multiplication) symbol, there are other ways to show multiplication.

5. What is a Variable?
The variables in an expression can be replaced with any number.
Once the variables have been replaced, you can evaluate, or find the value of, the algebraic expression.

6. What is a Term?
A term is a number, a variable, or a product or quotient of numbers and variables.
Example: 3 a 3a
3/a

7. What is a Coefficient?
A coefficient of a term is the number in front of the variable.
Example: 3a (3 is the coefficient) 4b 7x

8. Parts of an Expression Coefficients Variables Exponents 8c2 9x y8
Coefficients
Variables
Exponents
8c2 9x y8
12a2b3

9. Evaluating Expressions
When evaluating expressions, substitute the given number for the letter.

10. Evaluating Expressions
Evaluate when x = 2
3x + 2
2 + x + 7
Evaluate when x = 4 and y = 3
1) 2x + y
2) y + y + 4x

11. Evaluating Expressions
Evaluate when x = 5
4x/5 3x
2x + 6
9/x
Evaluate when x = 2 and y = 7
1. y + x
2. 9y – x
3. 7x + y
y + 2y

12. Evaluating Expressions
A Gentoo penguin can swim at a rate of 17 miles per hour. How many miles can a penguin swim in 4 hours? Use the expression rt, where r represents rate and t represents time.
A company charges $6 to make a pattern for an order of T-shirts and $11 for each T- shirt it produces from the pattern. The expression $11n + $6 represents the cost of n T-shirts with the same pattern. Find the total cost for 5 T- shirts with the same pattern.

13. Evaluating Expressions - Let´s Apply It
The perimeter of a rectangle can be found using the expression 2ℓ + 2w, where ℓ represents the length and w represents the width. Find the perimeter if = 6 units and w = 3 units.
The expression 3j shows the total cost with shipping for 3 pairs of jeans. Find the total cost if each pair of jeans costs $25.

14. Evaluating Expressions
Evaluate when x =4
2x + 7
8 + x 3

15. Evaluate each expression if m = 2 and n = 4.
1. m + m
n  m mn
4. 3m + 5
5. 2n + 2m
6. m • 0
 n
12  m
9. 5n  m
10. 6mn
4n  3
12. n  m + 8

16. STOP
End of day 1

17. Writing Algebraic Expressions p. 462-463 in your book

18. Writing Algebraic Expressions Key words
Addition
Sum
Increased by
Plus
More than
Subtraction
Difference
Minus
Decreased by
Less
Less then
Multiplication
Product
times
Division
Quotient
Divided by

19. Writing Algebraic Expressions

20. Writing Algebraic Expressions

21. Addition Examples 3 more than x the sum of 10 and a number c
a number n increased by 4.5

22. Subtraction Examples a number t decreased by 4
the difference between 10 and a number y
6 less than a number z

23. Multiplication Expressions
They should be written in side-by-side form, with the number always in front of the variable.
3a t c f

24. Multiplication Examples
the product of 3 and a number t
twice the number x
4.2 times a number e

25. Division Expressions

26. Division Examples the quotient of 3 and a number t
number x divided by 7

27. Let´s Apply It! 1) b divided by 9
2) a car travels at 75 mph for h hours
3) c more than 5
4) d decreased by 29
5) 8 times g
6) 17 less than the product of 3 and m
7) 2 less then the quotient of d and 16
8) 6 more than the difference of b and 5

28. Let´s Apply It! 1) 13 less than p 2) the sum of x and 9
3) p increased by 12
4) the quotient of k and 14
5)14 more than the difference of r and s
6) 7 less then h
7) 6 times f
8) 9 divided by t

29. STOP
End of day 2