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Published byBennett Russell Modified over 9 years ago

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Adding and Subtracting Integers “All things excellent are as difficult as they are rare” Spinoza

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Remember numbers can be positive or negative

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NO SIGN MEANS POSITIVE “ – ” means the number is negative “ + ” means the number is positive No sign usually means the number is really a positive number. Example 5 is really +5

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Adding and Subtracting positive numbers is just simple addition and subtraction Example: 2 + 3 = 5 is really saying "Positive 2 plus Positive 3 equals Positive 5" You could write it as (+2) + (+3) = (+5)

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AND…. Example: 6 − 3 = 3 is really saying "Positive 6 minus Positive 3 equals Positive 3" You could write it as (+6) − (+3) = (+3)

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Balloons and Weights This basket has balloons and weights tied to it: 1)The balloons pull up (POSITVE) 2) And the weights drag down (NEGATIVE)

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Here is what adding and subtracting positive numbers looks like You can add balloons (you are adding positive value) THE BASKET GETS PULLED UPWARDS (POSITIVE)

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Or you can take away balloons The basket gets pulled down

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What if you add negative numbers? You can add weights ( you are adding negative values The basket gets pulled downwards (NEGATIVE)

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What if you subtract negative numbers? You take away weights (you are subtracting negative values) The basket gets pulled upwards (POSITIVE)

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So…. Subtracting a Negative made the basket GO UP!?! So subtracting a Negative is the same as Adding!!!!

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General Rule for SUBTRACTING integers

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Example What is 6 – (-3) ? 6 – (-3) = 6 + 3 = 9

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NOW…. Solve 1) 14 – (-4) 2) 20 – (-10) 3) 15 – (-29)

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And Positive and Negative Together… Subtracting a positive or Adding a negative is SUBTRACTION

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Example 1) What is 6 – (+3) ? 6 – (+3) = 6 – 3 = 3 2) What is 5 + (-7) ? 5 + (-7) = 5 – 7 = -2

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Now solve… 1. 6 + -8 2. 10 + -5 3. 35 + -55

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The Rules Two like signs become a positive sign Two unlike signs become a negative sign

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Example + (+):3 + (+2) = 3 + 2 = 5 - ( - ): 6 – (-3) = 6 + 3 = 9 + ( - ): 7 + (-2) = 7 – 2 = 5 - ( + ): 8 – (+2) = 8 – 2 = 6

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So, all you have to remember is Two LIKE signs become a POSITVE sign Two UNLIKE signs become a NEGATIVE sign

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LET’S WATCH A VIDEO https://www.youtube.com/watch?v=lBscLuttQq0

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Exit Ticket 1) 43 – (-23) 2) 19 + - 38 3) -27 + 33 CHALLENGE: 1) -3.16 + 14 2) 13.4 – (-3.4)

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