2 3 Subtract Integers

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2 3 Subtract Integers

  1. 1. Subtracting Real Numbers Chapter 2.3 Subtracting is the same as adding a negative!
  2. 2. Warm Up <ul><li>What is the opposite of the following? </li></ul><ul><ul><li>-14 +5.2 -19 19 </li></ul></ul><ul><li>What is the absolute value of the following? </li></ul><ul><ul><li>-14 +5.2 -19 19 </li></ul></ul><ul><li>Find the sum </li></ul><ul><ul><li>-5 + 8= -9 + -12= </li></ul></ul>
  3. 3. Warm Up Answers <ul><li>Just change the signs </li></ul><ul><ul><li>+14 -5.2 +19 -19 </li></ul></ul><ul><li>Make them all positive </li></ul><ul><ul><li>+14 +5.2 +19 +19 </li></ul></ul><ul><li>Find the sum </li></ul><ul><ul><li>-5 + 8= +3 -9 + -12= -21 </li></ul></ul>
  4. 4. Subtracting Integers is really adding negatives <ul><li>Find the sum 9 + (-6) </li></ul><ul><li>Find the sum 9-(+6)? </li></ul><ul><li>What do you notice about the two number sentences above? </li></ul><ul><li>+3 </li></ul><ul><li>+3 </li></ul>
  5. 5. Make a subtraction statement into an addition statement <ul><li>Exchange the signs in the middle. </li></ul><ul><li>4 – (+5) = </li></ul><ul><li>-9 – (+8) = </li></ul><ul><li>-57 – (+25) = </li></ul><ul><li>+87 – (+88)= </li></ul><ul><li>A minus sign IS a negative sign. </li></ul><ul><li>4 + (-5) </li></ul><ul><li>-9 + ( - 8) </li></ul><ul><li>-57 +( - 25) </li></ul><ul><li>+87 + - 88 </li></ul>
  6. 6. Two negatives make a positive. <ul><li>4 – (+5) = 4 + (-5) </li></ul><ul><li> Opposite </li></ul><ul><li>statements </li></ul><ul><li>4 – (-5) = 4 + (+5) </li></ul><ul><li>Subtract a negative = add a positive. </li></ul>
  7. 7. How do you handle two negative signs in the middle? <ul><li>-9 – (-8) </li></ul><ul><li>Change them both to positive </li></ul><ul><li>-9 - (- 8) </li></ul><ul><li>-9 + (+8)= -1 </li></ul>
  8. 8. Try Some. Rewrite each statement <ul><li>-57 – (-25)= </li></ul><ul><li>-17 – (-21)= </li></ul><ul><li>7 – (-13)= </li></ul><ul><li>8 – (-33)= </li></ul><ul><li>-5 – 15 = </li></ul><ul><li>-57 + ( + 25) </li></ul><ul><li>-17 + ( + 21) </li></ul><ul><li>7 + ( + 13) </li></ul><ul><li>8 + ( + 33) </li></ul><ul><li>-5 + - 15 </li></ul>
  9. 9. And the answer is? <ul><li>-16 – (-21)= </li></ul><ul><li>-83 – (-17)= </li></ul><ul><li>83 – (-17)= </li></ul><ul><li>47 – (-12)= </li></ul><ul><li>-9 – 22 = </li></ul><ul><li>-16 + (+21)= -5 </li></ul><ul><li>-93 + (+17)= -76 </li></ul><ul><li>83 + (+17)= 100 </li></ul><ul><li>47 + (+12)= 59 </li></ul><ul><li>-9 + - 22 = - 31 </li></ul>
  10. 10. pg 71: 23 – 67 odds

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