diff --git a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
index 049665fe6..ec44ee4cc 100644
--- a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
+++ b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
@@ -705,7 +705,23 @@ variation of this quantity, and $`\Delta xxx`$ a macrosocpic variation.<br>
 \left(
 \dfrac{\overrightarrow{OM}(t+\Delta t)-\overrightarrow{OM}(t))}{\Delta t}
 \right)`$
-$`=\dfrac{\overrightarrow{OM}(t+dt)-\overrightarrow{OM}(t)}{dt}`$
+$`=\dfrac{\overrightarrow{OM}(t+dt)-\overrightarrow{OM}(t)}{dt}`$<br>
+<br>
+[ES] En las expresiones anteriores, también simplificaría la escritura. Algunos ejemplos :<br>
+[FR] Sur les expressions ci-dessus, cela permettrait aussi de simplifier l'écriture. Quelques exemples : :<br>
+[EN] On the expressions above, it would also simplify the writing. Some examples :<br>
+<br>
+$`d\left(\overrightarrow{OM}\right)(t)=d\left(A(t)\cdot\overrightarrow{e_x}\right)
++d\left(B(t)\cdot\overrightarrow{e_y}\right)`$
+$`=d\left(A(t)\right)\cdot\overrightarrow{e_x}
++d\left(B(t)\right)\cdot\overrightarrow{e_y}`$
+$`+A(t)\cdot d\overrightarrow{e_x} + B(t)\cdot d\overrightarrow{e_y}`$
+<br>
+$`d\overrightarrow{OM}(t)=d\left(A(t)\cdot\overrightarrow{e_x}
++B(t)\cdot\overrightarrow{e_y}\right)`$
+$`=dA(t)\cdot\overrightarrow{e_x}+A(t)\cdot d\overrightarrow{e_x}
++d(B(t)\cdot\overrightarrow{e_y}+ B(t)\cdot d\overrightarrow{e_y}`$
+