Bonjour
Varavarana
[tex]a)\ \begin{pmatrix}-2\\-8\end{pmatrix}=-2\begin{pmatrix}1\\4\end{pmatrix}\\\\\\\Longrightarrow\boxed{\overrightarrow{v}=-2\overrightarrow{u}}\\\\\\b)\ \begin{pmatrix}9\\6\end{pmatrix}=1,5\begin{pmatrix}6\\4\end{pmatrix}\\\\\\\Longrightarrow\boxed{\overrightarrow{v}=1,5\overrightarrow{u}}\\\\\\c)\ \begin{pmatrix}15\\-9\end{pmatrix}=-3\begin{pmatrix}-5\\3\end{pmatrix}\\\\\\\Longrightarrow\boxed{\overrightarrow{v}=-3\overrightarrow{u}}[/tex]
[tex]d)\ \begin{pmatrix}6\\18\end{pmatrix}=1,5\begin{pmatrix}4\\12\end{pmatrix}\\\\\\\Longrightarrow\boxed{\overrightarrow{v}=1,5\overrightarrow{u}}[/tex]