diff --git a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/40.classical-mechanics/10.main/textbook.fr.md b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/40.classical-mechanics/10.main/textbook.fr.md
index cb85a435f..58c46a6a7 100644
--- a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/40.classical-mechanics/10.main/textbook.fr.md
+++ b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/40.classical-mechanics/10.main/textbook.fr.md
@@ -253,8 +253,8 @@ remember to replace (auto-tra) with your initials (YYY).
 [FR] transformation de Galilée
 [EN] Galileo's transformations
 
-$`\mathbf{\begin{matrix}
-\left \{
+$`\mathbf{
+\left\{\begin{matrix}
 t'=t \\
 x'=x-V_x\,t \\
 y'=y-V_y\,t \\