Update textbook.fr.md

00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md

@@ -516,7 +516,7 @@ $`\displaystyle\quad\forall \overrightarrow{V}\in\mathcal{P}\quad \overrightarro
 * [FR] For the expression of a vector $`\vec{U}`$ in the base $`(\vec{e_1},\vec{e_2},...,\vec{e_n})`$,
 we shouldn't we use (http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=102-03-04) : <br>
 $`\overrightarrow{U}=\left(\begin{array}{l}U_1\\U_2\\U_3\end{array}\right)`$
-$`\displaystyle\overrightarrow{U}=\left(\begin{array}{l}U_1\\U_2\\U_3\end{array}\right)`$
+$`\displaystyle\overrightarrow{U}=\left(\begin{pmatrix}U_1\\U_2\\U_3\end{pmatrix}\right)`$
 instead of $`\overrightarrow{U}=\left|\begin{array}{l}U_1\\U_2\\U_3\end{array}\right.`$ as we do at INSA ?
 
 * [ES]  <br>