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1-2 Writing Algebraic Expressions
Warm UpWarm Up
Lesson PresentationLesson Presentation
Problem of the DayProblem of the Day
Lesson QuizzesLesson Quizzes
1-2 Writing Algebraic Expressions
Warm UpEvaluate each expression for the given values of the variables.
Which operation symbol goes with each word?
2318
1
+–
4. Sum
5. Product
6. Quotient7. Difference
1. 9y – 13 for y = 42. 6n + 2p for n = 2 and p = 3
3. 3x – y for x = 1 and y = 2
1-2 Writing Algebraic Expressions
Problem of the Day
Find a pair of numbers that fits the description. Their product is 221 and their sum is 30.
13, 17
1-2 Writing Algebraic Expressions
Learn to translate between algebraic expressions and word phrases.
1-2 Writing Algebraic Expressions
• 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
++
––
Word Phrases Expression
n + 5
x – 11
3m
or a 7a7
1-2 Writing Algebraic Expressions
Write an algebraic expression for each word phrase.
Additional Example 1: Translating Word Phrases into Math Expressions
A. 9 less than a number w 9 less than a number ww – 9w – 9
B. 3 increased by the difference of p and 53 increased by the difference of p and 53 + (p – 5)3 + p – 5
1-2 Writing Algebraic Expressions
Write an algebraic expression for each word phrase.
Check It Out: Example 1
A. the sum of a number h and 88 minus 4 the sum of h and 88 minus 4h + 88 – 4h + 88 – 4
B. the quotient of a number f and 6quotient of f and 6f 6
f6
1-2 Writing Algebraic Expressions
Write a word phrase for the algebraic expression 9 – 3c.
Additional Example 2: Translating Math Expressions into Word Phrases
9 – 3c
9 – 3 • c
9 minus the product of 3 and c
9 minus the product of 3 and c.
1-2 Writing Algebraic Expressions
Check It Out: Example 2
Write a word phrase for the algebraic expression 7 + 19b.
7 + 19b
7 + 19 • b
7 plus the product of 19 and b
7 plus the product of 19 and b.
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.
1-2 Writing Algebraic Expressions
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.
Additional Example 3: Writing and Evaluating Expressions in Word Problems
$10 dollars • n Combine n equal amounts of $10. $10n In dollars
20 $10 • 20 $20021 $10 • 21 $21022 $10 • 22 $22023 $10 • 23 $230
n $10 • n CostEvaluate for n = 20, 21, 22, and 23.
1-2 Writing Algebraic Expressions
Gasoline costs $3.59 per n gallons. What will the cost be for 10, 12, 14, and 15 gallons?
Check It Out: Example 3
$3.59 • n Combine n equal amounts of $3.59. $3.59n In dollars
10 $3.59 • 10 $35.9012 $3.59 • 12 $43.0814 $3.59 • 14 $50.2615 $3.59 • 15 $53.85
n $3.59 • n Cost
Evaluate for n = 10, 12, 14, and 15.
1-2 Writing Algebraic Expressions
Write a word problem that can be evaluated by the algebraic expression 27 + t, and evaluate the expression for t = 1.76.
Additional Example 4: Writing a Word Problem from a Math Expression
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
Write a word problem that can be evaluated by the algebraic expression 43 – d, and evaluate the expression for d = 10.24.
Check It Out: Example 4
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.
1-2 Writing Algebraic Expressions
Standard Lesson Quiz
Lesson Quizzes
Lesson Quiz for Student Response Systems
1-2 Writing Algebraic Expressions
Lesson Quiz
Write an algebraic expression for each word phrase.
1. 5 less than a number k
2. a number x divided by 11
3. 4 times the sum of n and 5
Write an algebraic expression to evaluate the word problem.
4. Karen buys n raffle tickets for $0.50 each. If she buys 13 of them, how much will they cost?
k – 5
4(n + 5)
0.50n; $6.50
x11
1-2 Writing Algebraic Expressions
Lesson Quiz for Student Response Systems
1. Identify the algebraic expression for the given word phrase.
20 less than a number r
A. 20 – r
B. r – 20
C. 20r – r
D. 20 – 20r
1-2 Writing Algebraic Expressions
2. Identify the algebraic expression for the given word phrase.
a number p divided by 16
Lesson Quiz for Student Response Systems
16p p
p 16
A. B.
16 p
C. p 16p
D.
1-2 Writing Algebraic Expressions
Lesson Quiz for Student Response Systems
3. Identify the algebraic expression for the given word phrase.
6 times the sum of r and 9
A. 6 + r + 9
B. 6r + 9
C. r(6 + 9)
D. 6(r + 9)
1-2 Writing Algebraic Expressions
Lesson Quiz for Student Response Systems
4. Identify the algebraic expression that evaluates the given word problem.
Alice buys x apples for $0.75 each. If she buys 24 of them, how much will they cost?
A. 0.75x; $9
B. 24x; $9
C. 0.75x; $18
D. 24x; $18