Scalar Product with Inverse Unity

Theorem
Let $\struct {G, +_G}$ be an abelian group whose identity is $e$.

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

Let $\struct {G, +_G, \circ}_R$ be an unitary $R$-module.

Let $x \in G$.

Then:
 * $\paren {-1_R} \circ x = - x$

Proof
Follows directly from Scalar Product with Inverse.

Also see

 * Basic Results about Modules
 * Basic Results about Unitary Modules