Holt CA Course 2

Writing Algebraic Expressions1-2

Warm UpWarm Up

California StandardsCalifornia Standards

Lesson PresentationLesson Presentation

PreviewPreview

Holt CA Course 2

Writing Algebraic Expressions1-2

Warm UpEvaluate each expression for the given values of the variables.

Which operation symbol goes with each word?

23

18

1

+

4. Sum 5. Product

6. Quotient 7. Difference

1. 9y – 13 for y = 4

2. 6n + 2p for n = 2 and p = 3

3. 3x – y for x = 1 and y = 2

Holt CA Course 2

Writing Algebraic Expressions1-2

AF1.1 Use variables and appropriate operations to write an expression, an equation, an inequality, or a system of equations or inequalities that represents a verbal description (e.g., three less than a number, half as large as area A).

California Standards

Holt CA Course 2

Writing Algebraic Expressions1-2

• 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

• 11 less than a number

• 3 multiplied by a number

• product of 3 and a number

• 7 divided into a number

• quotient of a number and 7

n + 5

x – 11

3 m or 3m

or a 7a7

Word Phrases Expression

+

–

Holt CA Course 2

Writing Algebraic Expressions1-2

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)

Holt CA Course 2

Writing Algebraic Expressions1-2

Write an algebraic expression for each word phrase.

Check It Out! Example 1

A. 88 times the difference of h and 4

88 times the difference of h and 488 • (h – 4)

88(h – 4)

B. the quotient of a number f and 6quotient of f and 6f 6

f6

Holt CA Course 2

Writing Algebraic Expressions1-2

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

Holt CA Course 2

Writing Algebraic Expressions1-2Check 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

Holt CA Course 2

Writing Algebraic Expressions1-2

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 Expressions1-2

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.

Additional Example 3: Writing and Evaluating Expressions in Word Problems

$10 • n Combine n equal amounts of $10. 10n Cost in dollars

20 10(20) $200 21 10(21) $210 22 10(22) $220 23 10(23) $230

Evaluate for n = 20, 21, 22, and 23.

n 10n Cost

Holt CA Course 2

Writing Algebraic Expressions1-2

Gasoline costs $1.99 per n gallons. What will the cost be for 10, 12, 14, and 15 gallons?

Check It Out! Example 3

$1.99 • n Combine n equal amounts of $1.99. 1.99n Cost in dollars

10 1.99(10) $19.90 12 1.99(12) $23.88 14 1.99(14) $27.86 15 1.99(15) $29.85

Evaluate for n = 10, 12, 14, and 15.

n 1.99n Cost

Holt CA Course 2

Writing Algebraic Expressions1-2

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.

Holt CA Course 2

Writing Algebraic Expressions1-2

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 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

Writing Algebraic Expressions1-2Lesson 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