\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
Pour \(\Vect{u}=\begin{pmatrix} 3 \\ 1\\ \end{pmatrix}\) et \(\Vect{v}=\begin{pmatrix} 2 \\ 4\\ \end{pmatrix}\), calcule :
\(2\Vect{u} \cdot (-3\Vect{v}) =\)