Friday, May 14, 2010

MATH INTEGERS RULE

REMEMBER THE FOLLOWING "PERSONALITY RULE" FOR Multiplying or Dividing INTEGERS...

Imagine there is a party where many people are hanging out....
If you have 2 positive people chatting, they will have a good or "positive" time, so      + x + = +


If you have 2 negative people chatting, they will also have a good time because after all they can both complain, but eventually they are having fun because they have like personalities. So....    - x - = +


BUT if you have a positive person hanging out with a negative person, they will not have a good time because they are not alike... so...
+ x - = -     or   - x + = -

This "Personality Rule" applies whether you multiply or divide integers...  and there you go, an easy way to remember the sign rules of integers.

Ms. Stewie

A REALLY GOOFY RAP ABOUT INTEGERS.... But if it helps you understand... awesome!



ANOTHER VIDEO ABOUT INTEGERS....


Adding Integers Rule:

All positive numbers...
* Add the numbers. The answer will always be positive.
(+8) + (+3) = +11

All negative numbers
* Add the numbers. The answer will always be negative.
(- 8) + (- 3) = - 11

Some positive and some negative numbers
(- 6) + (+5) =
* Ignoring whether the numbers are positive or negative, subtract the the smaller number from the larger number: 6 - 5 = 1

* Use the sign (+) or (-) of the larger number for your answer ~ in the case of this example, (-). Therefore 6 - 5 = - 1

With more that two numbers being added

(- 6) + (+5) + (+7) + (+4) + (- 3) =
* Add all the positive numbers: (+5) + (+7) + (+4) = +16
* Add all the negative numbers: (- 6) + (- 3) = - 9

* Ignoring whether the numbers are positive or negative, subtract the smaller number from the larger number: 16 - 9 = 7

* Use the sign (+) or (-) of the larger number for your answer ~ in the case of this example, (+). Therefore 16 - 9 = +7

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Subtracting Integers Rule

*Never subtract positive and negative numbers. Always turn a subtraction question into an addition question, and change number to the right to the opposite sign.

For example: (+7) - (-15) =

Change the subtraction symbol to an addition symbol: (+7) + (-15) =

*Also change the symbol of the number to the right of the new addition symbol. If the number was negative, it will now be positive, and if the number was positive, it will now be negative. In the case of this example, -15 now becomes +15, giving the new equation (+7) + (+15) =
Now follow the addition rules outlined above:

(+7) + (+15) =

All positive numbers

Add the numbers. The answer will always be positive.

(+7) + (+15) = (+22)

Let's try another subtraction equation together:

(+6) - (+13) =
Change the subtraction symbol to an addition symbol.

 Also change the symbol of the number to the right of the new addition symbol. If the number was negative, it will now be positive, and if the number was positive, it will now be negative. In the case of this example, +13 now becomes -13, giving the new equation
(+6) - (-13) =

Now follow the addition rules outlined above:

(+6) + (+13)     [Notice that we changed subtracting to adding, and changed -13 to +13.

Final example:

(- 6) - (+5) - (+7) - (+4) - (- 3) =

* Change the all subtraction symbols to an addition symbols:
* Also change the symbol of the number to the right of the new addition symbol. If the number was negative, it will now be positive, and if the number was positive, it will now be negative. The new equation will now read
(- 6) + (- 5) + (- 7) + (- 4) + (+3) =

*Now follow the addition rules outlined above:

(- 6) + (- 5) + (- 7) + (- 4) + (+3) =

* Add all the positive numbers: +3 = +3

* Add all the negative numbers: - 6 + - 5 + - 7 + - 4 = - 22
* Ignoring whether the numbers are positive or negative, subtract the smaller number from the larger number: 22 - 3 = 19

* Use the sign (+) or (-) of the larger number for your answer,  in the case of this example, (-). Therefore 22 - 3 = - 19

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Using the notes above, try adding and subtracting these practice questions.

a) (+3) + (+2) - (+1) =

b) (+1) + (+2) - (-3) =


c) (-3) - (+2) + (+1) =


d) (-3) - (+2) - (-1) =


e) (+3) - (+2) - (+1) =

Answer correctly, show work on loose leaf and include with your upcoming test for Unit 8 and receive bonus marks!!!





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1 comment:

  1. Your videos are awesome! I see they're from TeacherTube. Is YouTube blocked at your school, too?

    Your personality rules for multiplying are superb. One of my students had told me about something he learned, that "good things (+) happen to bad people (-) and that's bad (-).", etc, but the party reference is more relevant to high schoolers! haha!

    As a teacher, I have found negative numbers, especially addind and subtracting them, to be a huge stumbling block. I came up with a tool for adding integers of opposite signs, (ie: -12+7 or 7-12) that gives kids a manipulative to hold and that makes this abstract concept more concrete.

    You may find my tool useful. I found for myself, even though I teach 11th grade, the most mistakes my students make are with negative numbers. So I came up with this tool to help make dealing with positives less of a mystery. Plus, I found that always asking "ok, which number's absolute value is greater? Ok, your answer will take that sign. Now subtract the absolute values..." (you get the idea) was WAY too much to say every time!

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