Course 1

Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the Day

2-1 Variables and Expressions

Course 1

Warm UpSimplify.

1. 4 + 7 3 12. 87 15 53. 6(9 + 2) + 74. 35 7 5

2484

73

25

2-1 Variables and Expressions

Course 1

Problem of the Day

How can the digits 1 through 5 be arrangedin the boxes to make the greatest product?

4 3 1

5 2

2-1 Variables and Expressions

Course 1

Learn to identify and evaluate expressions.

2-1 Variables and Expressions

Course 1

Vocabularyvariableconstantalgebraic expression

2-1 Variables and Expressions

Course 1

A variable is a letter or symbol that represents a quantity that can change.

A constant is a quantity that does not change.

2-1 Variables and Expressions

Course 1

An algebraic expression contains one or more variables and may contain operation symbols. p 7 is an algebraic expression.

Algebraic Expressions NOT Algebraic Expressions

150 + y 85 ÷ 5

35 w + z 10 + 3 5

To evaluate an algebraic expression, substitute a number for the variable and then find the value.

2-1 Variables and Expressions

Course 1

Evaluate the expression to find the missing values in the table.

Additional Example 1A: Evaluating Algebraic Expressions

Substitute for y in 5 y.y 5 y

16

27

35

80 y = 16; 5 16 = 80

135

175

27 135

35 175

y = 27; 5 =

y = 35; 5 =

2-1 Variables and Expressions

Course 1

The missing values are 135 and 175.

Evaluate the expression to find the missing values in the table.

Additional Example 1B: Evaluating Algebraic Expressions

Substitute for z in z 5 + 4.z z 5 + 4

20

45

60

8 z = 20; 20 5 + 4 = 8

z = 45; __ 5 + 4 = __

z = 60; __ 5 + 4 = __

13

16

45 13

60 16

2-1 Variables and Expressions

Course 1

The missing values are 13 and 16.

Try This: Example 1A

Evaluate the expression to find the missing values in the table.

Substitute for x in x 9.x x 9

18

36

54

2 x = 18; 18 9 = 2

4

6

4

54 6

x = 36; 9 =

x = 54; 9 =

36

2-1 Variables and Expressions

Course 1

The missing values are 4 and 6.

Evaluate the expression to find the missing values in the table.

Try This: Example 1B

Substitute for z in 8 z + 2.z 8 z + 2

7

9

11

58 z = 7; 8 7 + 2 = 58

z = 9; 8 __+ 2 = __

z = 11; 8 __ + 2 = __

74

90

9 74

11 90

2-1 Variables and Expressions

Course 1

The missing values are 74 and 90.

Multiplication and division can be written without using the symbols and .

Instead of . . . You can write . . .

x 3x 3

35 ÷ y

x(3) 3x

35y

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

2-1 Variables and Expressions

Course 1

Find an expression for the table.

Additional Example 2A: Finding an Expression

39 13 = 3

n

39

52

65

3

4

5 65 13 = 5

52 13 = 4

n 13

An expression is n 13, or .n13

2-1 Variables and Expressions

Course 1

Find an expression for the table.

Additional Example 2B: Finding an Expression

7 • 4 = 28

p

4

6

8

28

42

56 7 • 8 = 56

7 • 6 = 42

7 • p

An expression is 7 • p, or 7p.

2-1 Variables and Expressions

Course 1

Find an expression for the table.

21 3 = 7

u

21

42

63

7

14

21 63 3 = 21

42 3 = 14

u 3

An expression is u 3, or .u3

Try This: Example 2A

2-1 Variables and Expressions

Course 1

Find an expression for the table.

Try This: Example 2B

4 • 5 = 20

n

5

8

11

20

32

44 4 • 11 = 44

4 • 8 = 32

4 • n

An expression is 4 • n, or 4n.

2-1 Variables and Expressions

Course 1

1. Evaluate each expression to find the missing

values in the tables.

Lesson Quiz: Part 1

x

10

7

5

x

1

3

5

7

21

35

x – 5

2. Find an expression for the table.

5

2

0

7x

2-1 Variables and Expressions

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Lesson Quiz: Part 2

3. Evaluate 8x for x = 5.

4. Evaluate 4x – 1 for x = 12.

40

47

2-1 Variables and Expressions

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