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1-1. Variables and Expressions. Homework. pp. 6-7 21 – 60 mult of 3. Pre-Algebra. Warm Up Evaluate. 1. 21  2(3). 2. 4 + 3  9 – 4(4). 3. 2(9) + [2(3) – 2(2)]. 4. 6(1.4) + (12 - 2²). 5. 9(2.9)  [5² - 3(4)]. Price. Trees. Price. Trees. $23.99. Dogwood. $22.99. Maple.

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  1. 1-1 Variables and Expressions Homework pp. 6-7 21 – 60 mult of 3 Pre-Algebra

  2. Warm Up Evaluate. 1. 21  2(3) 2. 4 + 3  9 – 4(4) 3. 2(9) + [2(3) – 2(2)] 4. 6(1.4) + (12 - 2²) 5. 9(2.9)  [5² - 3(4)]

  3. Price Trees Price Trees $23.99 Dogwood $22.99 Maple Elm $16.99 $26.99 Crab apple $19.99 $17.99 Birch Oak Problem of the Day Miss Smith obtained the prices below from the landscape company. She plans to buy five birch, two elm, one dogwood, and two oak trees. The landscape company will charge her $15 to plant each tree. How much will it cost? $337.90

  4. Review homework from last night

  5. Obj. - To evaluate algebraic expressions.

  6. A variable is a letter that represents a value that can change or vary. The coefficient is the number multiplied by the variable. The constant is the number that does not change. Coefficient Variable constant + 7

  7. An algebraic expression has one or more variables. To evaluate an algebraic expression, substitute a given number for the variable, and find the value of the resulting numerical expression.

  8. Example 1: Evaluate each expression for the given value of the variable. A.x – 5 for x = 12 12– 5 Substitute 12 for x. 7 Subtract. B.2y + 1 for y = 4 2(4) + 1 Substitute 4 for y. 8 + 1 Multiply. 9 Add.

  9. n Substitute Parentheses Multiply Subtract 5 6 7 Example 1C: Evaluate the expression for the given values of the variable. C.6(n + 2) – 4 for n = 5, 6, 7 6(5 + 2) – 4 6(7) – 4 38 42 – 4 6(6 + 2) – 4 6(8) – 4 44 48 – 4 6(7 + 2) – 4 6(9) – 4 50 54 – 4

  10. Example 2: Evaluate each expression for the given value of the variables. A.4x + 3y for x = 2 and y = 1 4(2) + 3(1) Substitute 2 for x and 1 for y. 8 + 3 Multiply. 11 Add. B.8.5 r – 2p for r = 2 and p = 5.5 8.5(2) – 2(5.5) Substitute 2 for r and 5.5 for p. 17 – 11 Multiply. 6 Subtract.

  11. Try This: Evaluate each expression for the given value of the variables. C.3x + 2y for x = 3 and y = 4 3(3) + 2(4) Substitute 3 for x and 4 for y. 9 + 8 Multiply. 17 Add. D.8q – 3.5r for q = 2.5 and r = 2 8(2.5) – 3.5(2) Substitute 2.5 for q and 2 for r. 20 – 7 Multiply. 13 Subtract.

  12. Example 3: Use the expression 1.8c + 32 to convert the boiling point temperature from degrees Celsius to degrees Fahrenheit. A.Boiling point of water at sea level: 100°C 1.8c + 32 1.8(100) + 32 Substitute 100 for c. 180 + 32 Multiply. 212 Add. 100°C = 212°F Water boils at 212°F.

  13. Lesson Quiz Evaluate each expression for the given values of the variables. 1. 6x + 9 for x = 3 2.x + 14 for x = 8 3. 4x + 3y for x = 2, y = 3 4. 1.6x – 2.9y for x = 19, y = 6 5. If n is the amount of money in a savings account, then the expression n + 0.03n can be used to find the amount in the account after it has earned interest for one year. Find the total in the account after one year if $500 is the initial amount. 27 22 17 13 $515

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