\begin{definition}[Definition:Scalar Multiplication by Negative Scalar]
Let $\mathbf a$ be a vector quantity.
Let $-m$ be a negative scalar quantity.
The operation of scalar multiplication by $-m$ of $\mathbf a$ is defined as:
:$-m \mathbf a := \paren {-m} \mathbf a = m \paren {-\mathbf a}$
that is, the negative of the scalar product of $m$ with $\mathbf a$.
\end{definition}