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Pre-Algebra 2-4 Solving Equations Containing Integers Today’s Learning Goal Assignment Learn to solve equations with integers.

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Pre-Algebra 2-4 Solving Equations Containing Integers Pre-Algebra: 2-4 HW Page 734 (Yes, page 734) #1-53 ODD

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Pre-Algebra 2-4 Solving Equations Containing Integers 2-4 Solving Equations Containing Integers Pre-Algebra Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

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Pre-Algebra 2-4 Solving Equations Containing Integers Warm Up Add, subtract, multiply, or divide. Pre-Algebra 2-4 Solving Equations Containing Integers 41 4 –42 36 –8 1. 24 + 17 2. 23 – 19 3. 12 · 3 4. 6(–7) 5. 6. –250 + (–85) –64 8 –335

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Pre-Algebra 2-4 Solving Equations Containing Integers Problem of the Day What are the numerical values of the, the, and the ? = 6, = 4, = 5 + + = 15 + – = 3 + – = 5 + – = 7

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Pre-Algebra 2-4 Solving Equations Containing Integers Learn to solve equations with integers.

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Pre-Algebra 2-4 Solving Equations Containing Integers When you are solving equations with integers, your goal is the same as with whole numbers: isolate the variable on one side of the equation. 0 +– – – + + 3 + (–3) = 0 a + (–a) = 0 Recall that the sum of a number and its opposite is 0. When you add the opposite to get 0, you can isolate the variable.

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Pre-Algebra 2-4 Solving Equations Containing Integers x = – 3 x – 3 = – 6 Add 3 to both sides.x – 3 + 3 = – 6 + 3 –5 + r = 9 r = 14 Add 5 to both sides.–5 + 5 + r = 9 + 5 x – 3 + 3 = – 3 Commutative Property 0 x – 3 = – 6 –5 + r = 9 Additional Example 1A & 1B: Adding and Subtracting to Solve Equations Solve. A. B.

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Pre-Algebra 2-4 Solving Equations Containing Integers –6 + 8 = n 2 = n The variable is already isolated. Add integers. –6 + 8 = n z + 6 = –3 z = –9 Add –6 to each side. z + 6 = –3 –6 Solve. C. D. Additional Example 1C & 1D: Adding and Subtracting to Solve Equations Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers p = –2 p – 7 = – 9 Add 7 to both sides. p – 7 + 7 = – 9 + 7 –2 + g = 5 g = 7 Add 2 to both sides.–2 + 2 + g = 5 + 2 p – 7 = – 9 –2 + g = 5 Solve. Try This: Example 1A & 1B p – 7 + 7 = – 2 Commutative Property 0 A. B.

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Pre-Algebra 2-4 Solving Equations Containing Integers –1 + 7 = r 6 = r The variable is already isolated. Add integers. –1 + 7 = r a + 9 = –9 a = –18 Add –9 to each side. Try This: Example 1C & 1D a + 9 = –9 –9 Solve. C. D.

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Pre-Algebra 2-4 Solving Equations Containing Integers x = –7 –5x = 35 Divide both sides by –5. –5x = 35 –5 Additional Example 2A: Multiplying and Dividing to Solve Equations Continued Solve. A.

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Pre-Algebra 2-4 Solving Equations Containing Integers Multiply both sides by –4. z = –20 = 5 z –4 –4 = –4 5 z –4 Additional Example 2B: Multiplying and Dividing to Solve Equations Continued Solve. B.

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Pre-Algebra 2-4 Solving Equations Containing Integers x = –6 –7x = 42 Divide both sides by –7. Try This: Example 2A –7x = 42 –7 Solve. A.

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Pre-Algebra 2-4 Solving Equations Containing Integers Multiply both sides by –3. z = –27 = 9 z –3 –3 = –3 9 z –3 Solve. B. Try This: Example 2

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Pre-Algebra 2-4 Solving Equations Containing Integers Sarah heard on the morning news that the temperature had dropped 26 degrees since midnight. In the morning, the temperature was –8°F. What was the temperature at midnight? Additional Example 3: Problem Solving Application

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Pre-Algebra 2-4 Solving Equations Containing Integers temperature at midnight morning temperature degrees that temperature dropped –= The answer is the temperature at midnight. List the important information: The temperature dropped 26 degrees since midnight. In the morning it was –8°F. 1 Understand the Problem Show the relationship or the information: Additional Example 3 Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers Write an equation and solve it. Let t represent the temperature at midnight and use the equation model. t – 26 = –8 Add 26 to both sides. t = 18 The temperature at midnight was 18° F. 2 Make a Plan Solve 3 + 26 Additional Example 3 Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers Look Back 4 The temperature at midnight was positive. Its value is less than the absolute value of the drop in temperature. This makes sense, since the morning temperature was negative. Additional Example 3 Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers Tim has two tug boats in a pulling contest. The boat on the left was pulling with a force of 23 tons. If the net force is 50 tons, what force is the boat on the right exerting on the rope? Try This: Example 3

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Pre-Algebra 2-4 Solving Equations Containing Integers The answer is the force that the right tug boat is exerting. List the important information: The boat on the left pulls with a force of 23 tons. The net force is 50 tons. Show the relationship of the information: 1 Understand the Problem Try This: Example 3 Continued net force left boat’s force = right boat’s force +

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Pre-Algebra 2-4 Solving Equations Containing Integers – Write an equation and solve it. Let f represent the force in tons. 2 Make a Plan 50 = 23 + f Solve 3 Add –23 to both sides. The right boat is exerting a force of 27 tons. 50 = 23 + f –23 27 = f Try This: Example 3 Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers Look Back4 The left tug boat was pulling at a force of 23 tons to the left. The total force on the tow rope was 50 tons. Since 23 tons is less than half the force, the tug boat on the right was advancing forward in a positive direction while the left tug boat was moving backward in a negative direction. Try This: Example 3 Continued

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Pre-Algebra 2-4 Solving Equations Containing Integers Lesson Quiz: Part 1 Solve. 1. t + 9 = –8 2. –15 = 3b 4. z – 16 = 30 x –4 3. = –7 t = –17 b = –5 x = 28 z = 46

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Pre-Algebra 2-4 Solving Equations Containing Integers A roller coaster descends down a hill at a rate of 80 feet per second. The bottom of the hill is 400 feet from the top. How long will it take the coaster riders to reach the bottom? Lesson Quiz: Part 2 5 seconds 5.

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