Question

The sum of $-1$and its additive inverse is _______

Answer 1

If any of the numbers are to be added with its additive inverse then the answer is to be zero

e.g$$\begin{gathered} 2+(-2)=0 \\ 5+(-5)=0 \\ 11+(-11)=0 \end{gathered}$$

In all the above examples the numbers are $2,5,11$ and their additive inverse are $-2,-5,-11$ and their sum is zero.

so the additive inverse of $-1$ is$1$.

Therefore, $1+(-1)=0$