R-10 All the Subtraction Rules!

R-10 All the Subtraction Rules!

 (+)-(+)
Find the difference between two #s and if the # you are subtracting from is larger, answer is +.


 (+)-(-)
Add together the absolute value of the 2 numbers to get the answer.
-Justification: Why does this work?

* I you do not have negatives to take away, you have to zeroate so you do not change the net value, but you get the negatives you need.

(-)-(-)

Change the #'s to the absolute value and find their difference. If the larger absolute value is first the answer is negative. If the larger absolute value is second the answer is +. 
Justification: If you don't have enough (-) to take away add parts of zeros until you do. Then take away (-). Remaining is the answer.  

(-)-(+)
Add absolute value of #'s and convert answer to negative. 

The class made 2 Rules: 

Different Sign
1.  (-)-(+) and (+)-(-) Add the absolute value. If the first # is (-), make the answer negative.

Same Sign
2. (+)-(+) and (-)-(-) Find the difference of the absolute value if the bigger # is first, the answer is positive.