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 ec44ee4cc..a537a4895 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
@@ -715,6 +715,12 @@ $`d\left(\overrightarrow{OM}\right)(t)=d\left(A(t)\cdot\overrightarrow{e_x}\righ
 +d\left(B(t)\cdot\overrightarrow{e_y}\right)`$
 $`=d\left(A(t)\right)\cdot\overrightarrow{e_x}
 +d\left(B(t)\right)\cdot\overrightarrow{e_y}`$
+$`+A(t)\cdot d\overrightarrow{e_x} + B(t)\cdot d\overrightarrow{e_y}`$<br>
+<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}