Granny Math
Adding Integers
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1plus2.jpg

1   +   2    =  3  

Thats nice, it did in the 1st grade.

neg2plusneg3.jpg
 2 reds + 3 reds = 5 reds or

- 2 + ( - 3)  =  - 5

We put - 3 in parenthesis just because

- 2 + -  3  = - 5would look funny.

 

- 4 + ( - 2)  =

neg4plusneg2.jpg

 

 

    - 4 + ( - 2)  = - 6

 

Negative  + Negative = negative

 

Now, what happens when you add a positive and a negative???

 

Well..

If you have one positive charge and a negative charge,

you can think of the positive as pushing to the right with one pound of pressure and the negative as pushing to the left with one pound of pressure.

pushingdifferent.jpg
                                             1 + ( - 1) = 0

 

                       - 2  + 2 = 

You can also think of writing a $2 check and then depositing $2 in the same checking account.  The net result (if there were no charges for writing checks without funds, etc.)--- NOTHING

  - 2  + 2 = 0

Any number and its opposite will ALWAYS  be 0.

 SO.

If you are adding   3  + ( - 2)  =
3plusneg2.jpg

  2 of the blues neutralize 2 of the reds  leaving 1 blue or 1 positive

3  + ( - 2)  =  1

 

What if you are adding 1 + ( - 5)

1plusneg5.jpg
 1 of the blues neutralizes 1 of the reds,
leaving 4 reds or - 4

 1 + ( - 5) = - 4

 If you are adding numbers or terms with different signs, you actually subtract the absolute values of the numbers , then take the sign of the term with the greater absolute value. 

(Above, 5 - 1 = 4 BUT the absolute value of - 5 is 5.

   5 > 1, so we took the negative  sign into our answer.)