Update textbook.fr.md

12.temporary_ins/40.classical-mechanics/40.n4/70.lagrangian-mechanics/07.coherence/textbook.fr.md

@@ -191,12 +191,12 @@ $`\quad=\dfrac{d}{dt}\dfrac{\partial\mathcal{L}}{\partial \dpt{x}_i}\cdot \delta
 
 
 
-$`\delta \mathcal{S}`$$`\;=\displaystyle\int_{t_1}^{t_2}
+$`\delta \mathcal{S}`$
+$`\;=\displaystyle\int_{t_1}^{t_2}
 \bigg[
  \dfrac{\partial\mathcal{L}}{\partial x_i}\cdot \delta x_i
  +\dfrac{d}{dt}\bigg(\,\dfrac{\partial\mathcal{L}}{\partial \dpt{x}_i}\cdot \delta x_i\bigg)
- -\dfrac{d}{dt}\dfrac{\partial\mathcal{L}}{\partial \dpt{x}_i}\cdot \delta x_i\bigg)\,dt
- \bigg]\;dt`$
+ -\dfrac{d}{dt}\dfrac{\partial\mathcal{L}}{\partial \dpt{x}_i}\cdot \delta x_i\bigg]\,dt`$