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Integer Addition & Absolute Values Lesson

Learn about adding integers, absolute values, and evaluating expressions in this interactive lesson. Practice using number lines and understanding when to add or subtract based on signs.

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Integer Addition & Absolute Values Lesson

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  1. Warm Up Problem of the Day Lesson Presentation Lesson Quizzes

  2. Warm Up Find each absolute value. 1.|8| 2. |–6| 3. |–9| 4. |–7| 5. |–12| 6. |53| 8 6 9 7 12 53

  3. Problem of the Day Jan’s yearly salary is $30,000, and it will be increased by $3,000 each year. Phil’s salary is $20,000, and it will be increased by $5,000 each year. In how many years will Jan and Phil both have the same yearly salary? 5 years

  4. Learn to add integers.

  5. –14 –12 –10 –8 –6 –4 –2 0 2 Additional Example 1A: Modeling Integer Addition Use a number line to find each sum. –7 + (–4) –7 +(–4) Start at 0. Move left 7 spaces. Then move left 4 more spaces. –7 + (–4) = –11

  6. –12 –10 –8 –6 –4 –2 0 2 4 6 8 Additional Example 1B: Modeling Integer Addition Use a number line to find each sum. –12 + 19 19 –12 Start at 0. Move left 12 spaces. Then move right 19 spaces. –12 + 19 = 7

  7. –14 –12 –10 –8 –6 –4 –2 0 2 Check It Out: Example 1A Use a number line to find each sum. –4 + (–5) –4 +(–5) Start at 0. Move left 4 spaces. Then move left 5 more spaces. –4 + (–5) = –9

  8. –12 –10 –8 –6 –4 –2 0 2 4 6 8 Check It Out: Example 1B Use a number line to find each sum. –7 + 12 12 –7 Start at 0. Move left 7 spaces. Then move right 12 spaces. –7 + 12 = 5

  9. To add two integers with the same sign, find the sum of their absolute values. Use the sign of the two integers. To add two integers with different signs, find the difference of their absolute values. Use the sign of the integer with the greater absolute value.

  10. Additional Example 2A: Adding Integers Using Absolute Values Find each sum. –4 + 8 The signs are different. Find the difference of the absolute values. –4 + 8 Think: 8 – 4 = 4. Use the sign of the integer with the greater absolute value. 4

  11. Additional Example 2B: Adding Integers Using Absolute Values Find each sum. 23 + (–35) The signs are different. Find the difference of the absolute values. 23 + (–35) Think: 35 – 23 = 12. Use the sign of the integer with the greater absolute value. –12

  12. Check It Out: Example 2A Find each sum. –5 + 3 The signs are different. Find the difference of the absolute values. –5 + 3 Think: 5 – 3 = 2. Use the sign of the integer with the greater absolute value. –2

  13. Check It Out: Example 2B Find each sum. –13 + (–24) The signs are the same. Find the sum of the absolute values. –13 + (–24) Think: 13 + 24 = 37. –37 Use the sign of the two integers.

  14. Helpful Hint When adding integers, think: if the signs are the same, find the sum. If the signs are different, find the difference. Additional Example 3: Evaluating Expressions with Integers Evaluate x + y for x = –42, y = 71. x + y Substitute for x and y. The signs are different. Think 71- 42 = 29 –42 + 71 Use the sign of the integer with the greater absolute value (positive). 29

  15. Check It Out: Example 3 Evaluate x + y for x = –24, y = 17. x + y Substitute for x and y. The signs are different. Think: 24 – 17 = 7. –24 + 17 –7 Use the sign of the integer with the greater absolute value (negative).

  16. Additional Example 4: Application The jazz band’s income from a bake sale was $286. Expenses were $21. Use integer addition to find the band’s total profit or loss. 286 + (–21) Use negative for the expenses. Find the difference of the absolute values. 286 – 21 265 The answer is positive. The band earned $265.

  17. Check It Out: Example 4 The French Club was raising money for a trip to Washington D.C. Their car wash raised $730. They had expenses of $52. Use integer addition to find the club’s total profit or loss. 730 + (–52) Use negative for the expenses. Find the difference of the absolute values. 730 – 52 678 The answer is positive. The club earned $678.

  18. Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems

  19. –14 –12 –10 –8 –6 –4 –2 0 2 Lesson Quiz: Part I Use a number line to find the sum. 1. –7 + (–6) Find each sum. 2. –15 + 24 + (–9) 3. –24 + 7 + (–3) 4. Evaluate x + y for x = –2 and y = –15. –13 0 –20 –17

  20. Lesson Quiz: Part II 5. The math club’s income from a bake sale was $217. Advertising expenses were $32. Use integer addition to find the club’s total profit or loss? $185 profit

  21. Lesson Quiz for Student Response Systems 1. Identify the number line that helps to find the sum. –5 + (–4) A. –1 B. –9

  22. Lesson Quiz for Student Response Systems 2. Identify the sum. –18 + 26 + (–8) A. –36 B. 0 C. 36 D. 52

  23. Lesson Quiz for Student Response Systems 3. Identify the sum. –26 + 8 + (–5) A. –23 B. –13 C. 0 D. 23

  24. Lesson Quiz for Student Response Systems 4. Evaluate x + y for x = –5 and y = –17. A. 22 B. 12 C. –12 D. –22

  25. Lesson Quiz for Student Response Systems 5. The cost of a guitar is $456. Helen has $178 with her. Use integer addition to identify how much more money she needs to buy the guitar. A. $296 B. $278 C. $196 D. $116

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