1-2 Writing Algebraic Expressions

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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

++

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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