Warm Up Problem of the Day Lesson Presentation Lesson Quizzes

Warm Up Evaluate each expression for the given values of the variables. Which operation symbol goes with each word? 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 4. Sum +  5. Product  6. Quotient – 7. Difference

Problem of the Day Find a pair of numbers that fits the description. Their product is 221 and their sum is 30. 13, 17

Learn to translate between algebraic expressions and word phrases.

  + – Word Phrases Expression n + 5 x – 11 3m a or a  7 7 a number plus 5 add 5 to a number n + 5 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 x – 11 11 less than a number a number decreased by 11 3 times a number 3 multiplied by a number 3m product of 3 and a number a number divided by 7 or a  7 a 7 7 divided into a number quotient of a number and 7

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

Check It Out: Example 1 Write an algebraic expression for each word phrase. A. the sum of a number h and 88 minus 4 the sum of h and 88 minus 4 h + 88 – 4 h + 88 – 4 B. the quotient of a number f and 6 quotient of f and 6 f  6 f 6

Additional Example 2: Translating Math Expressions into Word Phrases Write a word phrase for the algebraic expression 9 – 3c. 9 – 3c 9 – 3 • c 9 minus the product of 3 and c 9 minus the product of 3 and c.

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.

To solve a word problem, first interpret the action you need to perform and then choose the correct operation for that action.

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 evaluate what the cost would be if 20, 21, 22, or 23 people attended the function. $10 dollars • n Combine n equal amounts of $10. $10n In dollars n $10 • n Cost Evaluate for n = 20, 21, 22, and 23. 20 $10 • 20 $200 21 $10 • 21 $210 22 $10 • 22 $220 23 $10 • 23 $230

Check It Out: Example 3 Gasoline costs $3.59 per n gallons. What will the cost be for 10, 12, 14, and 15 gallons? $3.59 • n Combine n equal amounts of $3.59. $3.59n In dollars n $3.59 • n Cost 10 $3.59 • 10 $35.90 Evaluate for n = 10, 12, 14, and 15. 12 $3.59 • 12 $43.08 14 $3.59 • 14 $50.26 15 $3.59 • 15 $53.85

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.

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 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.

Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems

Write an algebraic expression for each word phrase. 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 x 11 4(n + 5) 0.50n; $6.50

Lesson Quiz for Student Response Systems 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

Lesson Quiz for Student Response Systems 2. Identify the algebraic expression for the given word phrase. a number p divided by 16 A. p 16 16p p B. p 16p C. 16 p D.

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)

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