Scared of subtraction involving negative integers? Don't be - remember, it's just addition in disguise!
The rule for subtraction is:
Add the OpPoSiTe!
Who likes fried chicken? It's one of my all-time favorites. :)
Img: thebittenword.com
So... what does fried chicken have to do with subtracting integers? Check out this cool chart from passyworldofmathematics.com:
Then, solve your problem as an addition problem. Here are a few examples:
-5 - 3 = ?
-5 + (-3) = -8 ---> Both numbers are the same sign, so we can add like normal and keep the sign.
7 - (-2) = ?
7 + 2 = 9 ---> Again, both numbers are the same sign, so we can add like normal and keep the sign.
4 - 8 = ?
4 + (-8) = ? ---> Now we've got addition with two different signs, so remember to use your absolute values!
The absolute values are 4 and 8. The difference between 4 and 8 is 4. Now, is it negative or positive? Look at the original number that had the greatest absolute value: -8. Since it's negative, we know the answer is -4.
If you are self-checking subtraction of integers tonight, here are the answers to the Quick Checks from 1-6 (pgs. 30 & 31):
1) a. -5
b. -1
c. -3
2) a. -4
b. -6
c. 5
3) a. 35
b. -106
c. -46
HaPpY SuBtRaCtInG!
