Subtracting Integers
Introduction
Subtracting integers means reducing the first value by the second amount in an equation. So in the equation:
We take 8, reduce it by 3, leaving us with 5. So, 8 - 3 = 5.
However, when we are working with negative values or a mixture of positive and negatives, things get a little more advanced.
Terms
Lesson
The golden rule to follow with subtracting integers is to combine the signs before you move on with the equation. The rules for combining signs are:
1) Negative and negative = addition
2) Positive and positive = addition
3) Negative and positive = subtraction
So, if you have the following equation:
You would first combine the signs. Since you have two negative (-) signs together, you convert that to an addition sign, meaning the equation looks like this:
We can then solve, since .
In the equation:
We can combine the signs. A negative and a positive sign together make a subtraction, so the equation looks like this:
, so that is the solution.
So, just remember, if the two signs are the same (- and -, or + and +) then the result is +; if the two signs are different (- and +, or + and -) then the result is -.
