#### Answer

$-\frac{1}{2}$

#### Work Step by Step

The additive inverse is the opposite of a number. The sum of a number and its additive inverse is 0.
Therefore, the additive inverse of $\frac{1}{2}$ is $-(\frac{1}{2})=-\frac{1}{2}$.
We can check to make sure the sum of these two numbers is 0.
$-\frac{1}{2}+\frac{1}{2}=\frac{1}{2}-\frac{1}{2}=0$