Unity Divides All Elements/Proof 2

Theorem
Let $\left({D, +, \circ}\right)$ be an integral domain whose unity is $1_D$.

Then unity is a divisor of every element of $D$:
 * $\forall x \in D: 1_D \mathop \backslash x$

Also:


 * $\forall x \in D: -1_D \mathop \backslash x$

Proof
This is a special case of Unit Divides All Elements, as Unity is Unit.

Furthermore, from Unity and Negative Subgroup of Units we also have that $-1_D$ is a unit of $D$.

Hence the result.