Download Holt CA Course 2

1-2
Writing Algebraic Expressions
Algebraic Expressions
Essential Question
How do verbal expressions
translate to algebraic
expressions?
Holt CA Course 2
1-2
Writing Algebraic Expressions
Warm Up
Evaluate each expression for the given values of
the variables.
1. 9y – 13 for y = 4 23
2. 6n + 2p for n = 2 and p = 3 18
3. 3x – y for x = 1 and y = 2 1
Which operation symbol goes with each word?
4. Sum +
6. Quotient
Holt CA Course 2

5. Product

7. Difference

1-2
Writing Algebraic Expressions
Word Phrases
+
–
•
•
•
•
a number plus 5
sum of a number and 5
5 more than a number
subtract 11 from a number
• difference of a number and 11
Expression
n+5
x – 11
• 11 less than a number

• 3 multiplied by a number

• 7 divided into a number
• product of 3 and a number
• quotient of a number and 7
Holt CA Course 2
3  m or 3m
a or a  7
7
1-2
Writing Algebraic Expressions
Additional Example 1: Translating Word Phrases into
Math Expressions
Write an algebraic expression for each word
phrase.
A. 9 less than a number w
9 less than a number w
w
–
9
w–9
B. 3 increased by the difference of p and 5
3 increased by the difference of p and 5
3
+
(p
–
5)
3 + (p – 5)
Holt CA Course 2
1-2
Writing Algebraic Expressions
Check It Out! Example 1
Write an algebraic expression for each word
phrase.
A. 88 times the difference of h and 4
88 times the difference of h and 4
88 •
(h – 4)
88(h – 4)
B. the quotient of a number f and 6
quotient of f and 6
f

6
f
6
Holt CA Course 2
Writing Algebraic Expressions
1-2
Additional Example 2: Translating Math Expressions
into Word Phrases
Write a word phrase for the algebraic
expression 9 – 3c.
9 – 3c
9
–
3
9
minus
•
c
the product of
3 and c
9 minus the product of 3 and c
Holt CA Course 2
Writing Algebraic Expressions
1-2
Check It Out! Example 2
Write a word phrase for the algebraic
expression 7 + 19b.
7 + 19b
7
+
19
7
plus
•
b
the product of
19 and b
7 plus the product of 19 and b
Holt CA Course 2
1-2
Writing Algebraic Expressions
To solve a word problem, first interpret the action
you need to perform and then choose the correct
operation for that action.
Holt CA Course 2
Writing Algebraic Expressions
1-2
Additional Example 3: Writing and Evaluating
Expressions in Word Problems
A restaurant leased its banquet hall for a function.
The cost was $10 per person. Write an algebraic
expression to determine what the cost would be if
n people attended the function. Then evaluate the
expression for 20, 21, 22, or 23 people.
$10 • n
10n
n
20
21
22
23
Holt CA Course 2
Combine n equal amounts of $10.
Cost in dollars
10n
10(20)
10(21)
10(22)
10(23)
Cost
$200
$210
$220
$230
Evaluate for n = 20,
21, 22, and 23.
1-2
Writing Algebraic Expressions
Check It Out! Example 3
Gasoline costs $1.99 per n gallons. What will
the cost be for 10, 12, 14, and 15 gallons?
$1.99 • n
1.99n
Combine n equal amounts of $1.99.
Cost in dollars
n
1.99n
Cost
10
12
14
15
1.99(10)
1.99(12)
1.99(14)
1.99(15)
$19.90
$23.88
$27.86
$29.85
Holt CA Course 2
Evaluate for n = 10,
12, 14, and 15.
1-2
Writing Algebraic Expressions
Additional Example 4: Writing a Word Problem
from a Math Expression
Write a word problem that can be evaluated
by the algebraic expression 27 + t, and
evaluate the expression for t = 1.76.
Possible answer:
Amed bought a new sweater for $27 plus sales
tax t. If the tax was $1.76, what was the total
cost of the sweater?
27 + t
27 + 1.76 = 28.76
Substitute 1.76 for t.
The total cost of the sweater was $28.76.
Holt CA Course 2
1-2
Writing Algebraic Expressions
Check It Out! Example 4
Write a word problem that can be evaluated
by the algebraic expression 43 – d, and
evaluate the expression for d = 10.24.
Possible answer:
Tina bought a new jacket for $43 minus a store
credit. If the store credit was $10.24, what did
Tina pay for the jacket?
43 – d
43 – 10.24 = 32.76 Substitute 10.24 for d.
Tina paid $32.76 for the jacket.
Holt CA Course 2