Scalar Product with Inverse Unity

Theorem
Let $\left({G, +_G}\right)$ be an abelian group whose identity is $e$.

Let $\left({R, +_R, \times_R}\right)$ be a ring with unity whose zero is $0_R$ and whose unity is $1_R$.

Let $\left({G, +_G, \circ}\right)_R$ be an unitary $R$-module.

Let $x \in G$.

Then:
 * $\left({- 1_R}\right) \circ x = - x$

Proof
Follows directly from Scalar Product with Inverse.

Also see

 * Basic Results about Modules
 * Basic Results about Unitary Modules