1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up
Simplify.
 3  1
2. 87  15  5
3. 6(9 + 2) + 7
4. 35  7  5 24 84 73 25

3. Problem of the Day
How can the digits 1 through 5 be arranged in the boxes to make the greatest product? 

4. Learn to identify and evaluate expressions.

5. Vocabulary
variable
constant
algebraic expression
evaluate

6. A variable is a letter or symbol that represents a quantity that can change.
A constant is a quantity that does not change.

7. Algebraic Expressions NOT Algebraic Expressions
An algebraic expression contains one or more variables and may contain operation symbols. So p  7 is an algebraic expression.
Algebraic Expressions
NOT Algebraic Expressions
150 + y
85 ÷ 5
35  w + z
 5
To evaluate an algebraic expression, substitute a number for the variable and then find the value.

8. Additional Example 1A: Evaluating Algebraic Expressions
Evaluate the expression to find the missing values in the table. y
5  y 16 27 35 80
Substitute for y in 5  y.
y = 16; 5  16 = 80
y = 27; 5  = 27
135
135
175
y = 35; 5  = 35
175
The missing values are 135 and 175.

9. Additional Example 1B: Evaluating Algebraic Expressions
Evaluate the expression to find the missing values in the table. z
z  20 45 60
Substitute for z in z 
z = 20; 20  = 20
z = 45; __  = __ 45 25 25 28
z = 60; __  = __ 60 28
The missing values are 25 and 28.

10. Check It Out: Example 1A
Evaluate the expression to find the missing values in the table. x
x  9 18 36 54 2
Substitute for x in x  9.
x = 18; 18  9 = 2
x = 36;  9 = 36 4 4 6 6
x = 54;  9 = 54
The missing values are 4 and 6.

11. Check It Out: Example 1B
Evaluate the expression to find the missing values in the table. z
8  z + 23 7 9 11 64
Substitute for z in 8  z + 23.
z = 7; 8  = 64 9 80 80
z = 9; 8  __+ 8 = __ 96
z = 11; 8  __ + 8 = __ 11 96
The missing values are 80 and 96.

12. You can write multiplication and division expressions without using the symbols  and .
Instead of . . .
You can write . . .
x  3
x  3
x(3) 3x 35 y
35 ÷ y
When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.”
Writing Math

13. Additional Example 2: Evaluating Expressions with Two Variables
A rectangle is 4 units wide. How many square units does the rectangle cover if it is 3, 4, 5, or 6 units long?
Make a table to help you find the number of square units for each length. l w
l x w 3 4 12 5 6
3 x 4 = square units 12 16
4 x 4 = square units 16 20
5 x 4 = square units 20 24
6 x 4 = square units 24
The rectangle will cover 12, 16, 20, or 24 square units.

14. l w l x w Check It Out: Example 2
A rectangle is 3 units wide. How many square units does the rectangle cover if it is 2, 3, 4, or 5 units long?
Make a table to help you find the number of square units for each length. l w
l x w 2 3 6 4 5
2 x 3 = square units 6 9
3 x 3 = square units 9 12
4 x 3 = square units 12 15
5 x 3 = square units 15
The rectangle will cover 6, 9, 12, or 15 square units.

15. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

16. 1. Evaluate the expression to find the missing values in the table. 95
Lesson Quiz x
x2 – 5 10 7 5
1. Evaluate the expression to find the missing values in the table. 95 44 20 l w
l x w 2 6 3 4 5
2. A rectangle is 6 units wide. What is the area of the rectangle cover if it is 2, 3, 4, or 5 units long? 12 18 24 30

17. Lesson Quiz for Student Response Systems
1. Evaluate the expression to find the missing values in the table.
A. 67, 97, 112
B. 67, 77, 92
C. 47, 77, 92
D. 47, 77, 112 x
5x + 22 9 15 18

18. Lesson Quiz for Student Response Systems
2. A rectangle is 8 units wide. How many square units does the rectangle cover if it is 5, 6, 7, or 8 units long?
A. 40, 46, 56, 66
B. 40, 48, 56, 64
C. 13, 14, 15, 16
D. 13, 15, 17, 19 l w
l x w 5 8 6 7