Download September 21, 2015 Pre-Algebra

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
Homework: Page 12 #11-31 all.
1-2 Writing Algebraic Expressions
Which operation symbol goes with each word?
1. Sum +
2. Product


3. Quotient
4. Difference
–
1-2 Writing Algebraic Expressions
Word Phrases
+
–


•
•
•
•
•
•
•
•
•
•
a number plus 5
add 5 to a number
sum of a number and 5
5 more than a number
a number increased by 5
a number minus 11
subtract 11 from a number
difference of a number and 11
11 less than a number
a number decreased by 11
• 3 times a number
• 3 multiplied by a number
• product of 3 and a number
• a number divided by 7
• 7 divided into a number
• quotient of a number and 7
Expression
n+5
x – 11
3m
a or a  7
7
1-2 Writing Algebraic Expressions
Write an algebraic expression for each word
phrase.
5. 9 less than a number w
9 less than a number w
w
–
9
w–9
6. 3 increased by the difference of p and 5
3 increased by the difference of p and 5
3
+
(p
–
5)
3+p–5
1-2 Writing Algebraic Expressions
Write an algebraic expression for each word
phrase.
7. the sum of a number h and 88 minus 4
the sum of h and 88 minus 4
h
+
88 – 4
h + 88 – 4
8. the quotient of a number f and 6
quotient of f and 6
f

6
f
6
1-2 Writing Algebraic Expressions
9. 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.
1-2 Writing Algebraic Expressions
10. 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.
1-2 Writing Algebraic Expressions
11. A restaurant leased its banquet hall for a
function. The cost was $10 per person. Write
an algebraic expression to evaluate what the
cost would be if 20, 21, 22, or 23 people
attended the function.
$10 dollars • n
$10n
n
20
21
22
23
$10
$10
$10
$10
$10
•
•
•
•
•
n
20
21
22
23
Combine n equal amounts of $10.
In dollars
Cost
$200
$210
$220
$230
Evaluate for n = 20,
21, 22, and 23.
1-2 Writing Algebraic Expressions
12. Gasoline costs $3.59 per n gallons. What
will the cost be for 10, 12, 14, and 15 gallons?
$3.59 • n
$3.59n
n
10
12
14
15
Combine n equal amounts of $3.59.
In dollars
$3.59 • n
$3.59 • 10
$3.59 • 12
$3.59 • 14
$3.59 • 15
Cost
$35.90
$43.08
$50.26
$53.85
Evaluate for n = 10,
12, 14, and 15.
1-2 Writing Algebraic Expressions
13. 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.
1-2 Writing Algebraic Expressions
14. 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 was the total cost of the jacket?
43 – d
43 – 10.24 = 32.76
Substitute 10.24 for t.
The total cost of the jacket was $32.76.