Sufficient Condition for Vector Equals Inverse iff Zero

Theorem
Let $\left({\mathbf V, +, \circ}\right)_{\mathbb F}$ be a vector space over $\mathbb F$, as defined by the vector space axioms.

Let $\mathbb F$ be infinite.

Then:


 * $\forall \mathbf v, -\mathbf v \in \mathbf V: \mathbf v = - \mathbf v \iff \mathbf v = \mathbf 0$

Sufficient Condition
Utilizing the vector space axioms:

By hypothesis, $\mathbb F$ is infinite.

By Characteristic of Division Ring, $\operatorname{Char} \left({\mathbb F}\right) = 0$, so $-2 \cdot 1_{\mathbb F} \ne 0$.

Thus from Vector Product is Zero only if Factor is Zero, $\mathbf v = \mathbf 0$.