Yesterday we talked about integer opposites and how they are the opposite signs of each other, such as 3 and -3. Today we will learn about the term additive inverses. This is just another name for the opposite. The rule states that when you add two opposites or additive inverses together, you get zero. Let's see if this is true.
Ex. 3 and -3
3 + -3 = 0
This is true. It is also the same if we were to use variables such as x.
x + (-x) = 0
When we add one negative to one positive, we get what is called a zero pair.
In a way, they cancel each other out.
There are a couple of rules you need to remember when adding integers. Since integers can be either positive or negative, it is very important that we follow the rules with their signs.
When adding integers of the same sign, the sum of two positive integers is positive. The sum of two negative integers is negative. When they are different signs, you can find the difference of their absolute values. The sum has the same sign of the integer with the greater absolute value.
Ex.
(-2) + (-5)
Since they both have the same sign, we just add them together and they keep the negative sign.
The answer to this example would be (-7).
Ex.
(-12) + 8
Since they are of different signs, we take the absolute value of each one and then subtract the smaller one from the larger one.
12 - 8 = 4
Now, since the one with the larger absolute value was -12, our answer will still have to be negative. So the answer to this example is -4.
We will discuss this more in class.
Homework for this section is Pg. 26 14-50 evens
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