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Wednesday, January 15, 2014

Jonathan's multiplying integers

The Sign Rule
When you multiply integers with the same value (+ or -) the product  will always be positive. ex. (-5)x(-4)=+20 or 7x9=49
When the value of the integers are different (+,-) the product will be negative. ex. (+2)x(-8)=-16

Here are 3 more examples so you can understand the sign rule a little bit better-
(-4)x(+2)= -8                          since these integers have opposite signs, the answer will be a negative
remove 4 groups of 2
Now we need to make zero pairs because you can't remove -4 groups of 2.
 <(++++) (++++)>  you need to circle the groups and make arrows so you know if they are coming/going
      - - - - - - - -
Now you are left with -8 which is the answer.

+4x+8= +32                                the numbers have the same sign which means the answer will be positive
4 groups of 8
So all we need to do is make 4 groups of 8
(++++++++) (++++++++) (++++++++) (++++++++)
        ^                     ^                     ^                ^      
Your answer is 32           

(-3)x(-3)= +6                              3x3=6. You need 6 zero pairs
remove 3 groups of -3
       + + + + + +
 < ( - -  -)( -  -  -)>
Sign Rule Continue
When you have an even amount of (-) signs the product is positive. ex. (-5)x(+5)x(-5)=+125
When there are odd number of (-) signs the product is negative. ex. (+5)x(-5)x(+5)=-125

Let's do 2 more examples so you know this concept more well-
4x(-2)x(-2)=
4 groups of -2 groups of -2. This looks difficult so lets do this into parts.
4 groups of -2    (--) (--) (--) (--) this is -8  Now lets rephrase the question ( you don't have to do this step)
                           ^     ^    ^     ^
 It's now -8x-2= +16                8x2=16=16 zero pairs                      + + + + + + + + + + + + + + + +           remove 8 groups of -2                                            <  ( -  -) ( -  -) (-  -)  (- -)  (-  -)  (-  -)  (- -)  (-  -)>

(-3)x4x1=
remove 3 groups of 4 groups of 1
remove 3 groups of 4                               <( +++)(+++)(+++)(+++)>        = -12
                                                                     - - - - - - - - - - - -
-12x1=-12
remove 12 groups of 1                        < (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+)>
 -12 is the answer                                    -     -    -    -     -   -    -     -    -    -    -    -

Thanks for looking at my scribe post. Be sure to comment on my work and give me any suggestions if I made a mistake. Here's a video about the sign rule that will make you a genius. 

1 comment:

  1. Great job! i liked how you included the sign rules so we know more already and your explanation was great, it's easy to understand, your pictures were good, that really helped understand more of what you're trying to say, good job!

    ReplyDelete

 

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