diff --git a/01.curriculum/01.physics-chemistry-biology/04.Niv4/04.electromagnetism/02.electromagnetic-waves-vacuum/02.electromagnetic-waves-vacuum-main/textbook.fr.md b/01.curriculum/01.physics-chemistry-biology/04.Niv4/04.electromagnetism/02.electromagnetic-waves-vacuum/02.electromagnetic-waves-vacuum-main/textbook.fr.md
index 50b43f3ad..db7963f6f 100644
--- a/01.curriculum/01.physics-chemistry-biology/04.Niv4/04.electromagnetism/02.electromagnetic-waves-vacuum/02.electromagnetic-waves-vacuum-main/textbook.fr.md
+++ b/01.curriculum/01.physics-chemistry-biology/04.Niv4/04.electromagnetism/02.electromagnetic-waves-vacuum/02.electromagnetic-waves-vacuum-main/textbook.fr.md
@@ -21,7 +21,7 @@ $`\Delta \overrightarrow{X} - \dfrac{1}{v_{\phi}} \; \dfrac{\partial^2 \;\overri
 
 L'expression de l'opérateur $`\Delta`$ en fonction des opérateurs $`grad`$, $`div`$ et $`rot`$ est :
 
-$`\Delta`$ = $`\overrightarrow{grad} \left(div\right) - \overrightarrow{rot}\, \left(\overrightarrow{rot}\right)`$
+$`\Delta =`\overrightarrow{grad} \left(div\right) - \overrightarrow{rot}\, \left(\overrightarrow{rot}\right)`$
 
 
 ### Propagation du champ électromagnétique