**Additive Inverse**

For any real number *a*, the number 2*a *is the additive inverse of *a*.

Change the sign of a number to get its additive inverse. *The sum of a number*

*and its additive inverse is always 0.*

* *

The symbol “-” can be used to indicate any of the following:

**a. **a negative number, such as -9 or -15;

**b. **the additive inverse of a number, as in “- 4 is the additive inverse of 4”;

**c. **subtraction, as in 12 – 3.

In the expression – (-5), the symbol “-” is being used in two ways: the

first – indicates the additive inverse of -5, and the second indicates a negative

number, -5. Since the additive inverse of – 5 is 5, then – (- 5) = 5. This

example suggests the following property.

** **For any real number *a*, – **(**– *a***) **= *a***.**