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Subtracting Positive and Negative Integers

Subtracting Positive and Negative Integers. WARM-UP:. 1.) (-5) + (-26) = 2.) (-18) + 7 = 3.) Write a variable expression for: r less than 12 4.) -40 + 9 = 5.) 4 + (-36) =. Let's review what we learned in the last lesson.

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Subtracting Positive and Negative Integers

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  1. Subtracting Positive and Negative Integers Confidential

  2. WARM-UP: 1.) (-5) + (-26) = 2.) (-18) + 7 = 3.) Write a variable expression for: r less than 12 4.) -40 + 9 = 5.) 4 + (-36) = Confidential

  3. Let's review what we learned in the last lesson. Confidential

  4. Confidential

  5. Confidential

  6. Confidential

  7. TODAY we will be studying 2 methods to learn how to subtract integers. METHOD 1 - Zero Pairs + - + - - + - - Remember that the red chips are NEGATIVE. The grey chips are POSITIVE. Confidential

  8. Let's subtract 6 - 2 = We begin with 6 POSITIVE (grey) chips. + + + + + + next page Confidential

  9. Let's subtract 6 - 2 = Then we take away (or Subtract) 2 POSITIVE chips. + + + + + + next page Confidential

  10. Let's subtract 6 - 2 = We are left with 4 POSITIVE (Grey) chips. + + + + So..... 6 - 2 = 4 Confidential

  11. Now, let's subtract (-5) - (-4) = We begin with 5 NEGATIVE (or red) chips. - - - - - next page Confidential

  12. Now, let's subtract (-5) - (-4) = Then, we take away (or Subtract) 4 NEGATIVE chips. - - - - - next page Confidential

  13. Now, let's subtract (-5) - (-4) = And we are left with 1 NEGATIVE (red) chip. - Therefore, (-5) - (-4) = -1 Do you have any questions so far? Confidential

  14. SOMETIMES we need to add Zero Pairs in order to subtract or take away chips. For example, let's subtract 5 - (-3) = We begin with 5 POSITIVE (grey) chips. + + + + + next page Confidential

  15. 5 - (-3) = + + + We begin with 5 POSITIVE (grey) chips. + + + Now, we need to take away (or Subtract) 3 NEGATIVE (red) chips but we don't have any!! So we must ADD 3 Zero Pairs............... + + + - - - Confidential next page

  16. 5 - (-3) = + + + + + Now, we can take away (or Subtract) the 3 NEGATIVE (red) chips. + + + - - - And we are left with 8 POSITIVE (grey) chips. Therefore, 5 - (-3) = 8 Confidential

  17. You try this one… (-4) - 1 = Use your pen to draw the red and grey circles. Confidential

  18. Try 4 - (-2) = Use your pen to draw the red and grey circles. Confidential

  19. METHOD 2 - Rule for Subtracting Integers When we subtract an integer, we add its opposite. For example, (-10) - 7 = (-10) + (-7) = (-17) we add its opposite Confidential

  20. Of course, if we are going to ADD its opposite, we must remember the rules for ADDING INTEGERS. LET'S REVIEW Adding the Same Sign - The sum of 2 positive numbers is POSITIVE. The sum of 2 negative numbers is NEGATIVE. Adding Different Signs - 1. Find the absolute value of the 2 numbers. 2. Subtract the smaller number from the larger number. 3. Take the sign of the larger number for your answer. Confidential

  21. Let's try a few more subtraction problems. Remember the RULE - When we subtract an integer, we add its opposite. 9 - (-6) = 9 + 6 = 15 its opposite we add Confidential

  22. You try a few. (-4) - (-4) = (-2) - 8 = 12 - (-3) = Confidential

  23. 1.) Can you find the missing numbers? -32 + = 65 47 - = 80 Confidential

  24. 2.)Anne is 8 years older than Jane and 3 years older than Mary. The sum of their ages is 67. How old is each person? Confidential

  25. 3.) Use these digits (4, 7, 9) to make as many 3 digit numbers as possible. You may only use each digit only one time in each number. Confidential

  26. Let's see how well you understood the lesson today. Find each difference. 1.) -13 - 13 = 2.) 9 - (-8) = 3.) 28 - 16 = Confidential

  27. 4.) 12 - 15 = 5.) 0 - (-47) = 6.) -190 - 82 = Confidential

  28. 7.) (-12) - (-26) = 8.) 4 - (-60) = 9.) 22 - 38 = 10.) (-109) - 10 = Confidential

  29. Let's review what we learned today. We looked at 2 different methods for SUBTRACTING integers. METHOD 1 - Using Zero Pairs - + Confidential

  30. SOMETIMES we need to add Zero Pairs in order to subtract or take away chips. 3 - (-1) = Begin with 3 POSITIVE chips + + + Add 1 ZERO PAIR + - Now we can take away 1 NEGATIVE chip And you're left with 4 POSITIVE chips 3 - (-1) = 4 Confidential

  31. Confidential

  32. Great job today! Remember to practice what you learned! Confidential

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