AF 1.1*((
Use letters,
boxes, or other symbols to stand for any number in
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DOJHEUDLFH[SUHVVLRQV
simple expressions or equations (e.g., demonstrate an
understanding and use the concept of a variable).
UNDERLYING SKILLS AND CONCEPTS:
meaning of operations;
understand the meaning of word
problems
Use Variables in Expressions
a
K
ey Ide
An expression is a mathematical phrase that is made up numbers,
parentheses, and operation signs.
An expression that contains a variable, is an algebraic expression.
E x am p l E
1
Susan is 3 years older than her brother Tim.
Let y ! Tim’s age.
How do you show Susan’s age in terms of Tim’s age?
If y ! Tim’s age, then y " 3 ! Susan’s age.
E x am p l E
2
D – © CSL Associates, Inc. All rights reserved.
Write an expression for 4 times a number.
4#n
page 212
Chapter 18 – Lesson 4
Name
P RAC T I C E
Write an expression for each phrase.
1. a number plus 7
2. The difference of a number and 4
n7
3. six times a number
n4
4. 9 divided by a number
6n
5. 7 times a number minus 2
9n
6. ten plus the product of 5 and a
number
D – © CSL Associates, Inc. All rights reserved.
7n2
7. Grandmother’s age is 5 times Tim’s
age. How do you show
grandmother’s age?
10 5 n
8. Tony is twice as old as Karin’s age
plus 4. How do you show Tony’s
age?
5t
Math
Reasoning
Use Variables in Expressions
2 (k 4)
MR 1.1
9. Explain the difference between 5 less than a number and 5 less a number.
n 5 is 5 less than a number. 5 n is 5 less a number.
Chapter 18 – Lesson 4
page 213
MCX94.HW.CL.G4.FM&Lesson.v211
8/2/04
19:16
Page 144
Name
P RAC T I C E
…at home!
Write an expression for each phrase.
1. a number minus 9
2. The difference of a number and 8
n9
n8
3. four times a number
4. 12 divided by a number
4n
12 n
(9 n) 5 or 9 (n 5)
7. Grandfather’s age is 6 times Tim’s
age. How do you show
grandfather’s age?
6t
Math
Reasoning
6. two plus the difference of 5 and a
number
2 (5 n)
8. Tony is three times as old as
Karin’s age minus 5. How do you
show Tony’s age?
3 (k 5)
Use Variables in Expressions
MR 1.1
9. Explain the difference between 4 less than a number and 4 less a number.
n 4 is 4 less than a number. 4 n is 4 less a number.
page 144
Home Resource and Homework
Chapter 18 Lesson 4
D – © CSL Associates, Inc. All rights reserved.
5. 9 times a number plus 5
MCX94TEG4Ch01_32.v8.5.2 2/26/01 19:03 Page 393
Name
P RAC T I C E
Write an expression for each phrase.
1. a number plus 7
2. The difference of a number and 4
n7
n4
3. six times a number
4. 9 divided by a number
6n
9n
5. 7 times a number minus 2
6. ten plus the product of 5 and a
number
D – © CSL Associates, Inc. All rights reserved.
7 n 2 or 7 (n 2)
7. Grandmother’s age is 5 times Tim’s
age. How do you show
grandmother’s age?
10 5 n
8. Tony is twice as old as Karin’s age
plus 4. How do you show Tony’s
age?
5t
Math
Reasoning
2 (k 4)
Use Variables in Expressions
MR 1.1
9. Explain the difference between 5 less than a number and 5 less a number.
n 5 is 5 less than a number. 5 n is 5 less a number.
Chapter 18 – Lesson 4
Student Book Page
page 213
Name
P RAC T I C E
…at home!
Write an expression for each phrase.
1. a number minus 9
2. The difference of a number and 8
n9
n8
3. four times a number
4. 12 divided by a number
4n
12 n
(9 n) 5 or 9 (n 5)
7. Grandfather’s age is 6 times Tim’s
age. How do you show
grandfather’s age?
6t
Math
Reasoning
6. two plus the difference of 5 and a
number
2 (5 n)
8. Tony is three times as old as
Karin’s age minus 5. How do you
show Tony’s age?
3 (k 5)
Use Variables in Expressions
MR 1.1
9. Explain the difference between 4 less than a number and 4 less a number.
n 4 is 4 less than a number. 4 n is 4 less a number.
page 144
Home Resource and Homework
Chapter 18 Lesson 4
D – © CSL Associates, Inc. All rights reserved.
5. 9 times a number plus 5