# Post History

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**#2: Post edited**

- In the post, actually $\dot{y}=\frac{dy}{dx}$. So,
- $$\int_{x_1}^{x_2}\frac{\partial f}{\partial \dot{y}}\frac{\partial \dot{y}}{\partial \alpha}\mathrm dx=\int_{x_1}^{x_2}\frac{\partial f}{\partial \dot{y}}\frac{\partial^2 y}{\partial x \partial \alpha}\mathrm dx$$
~~In the equation, they just wrote $\frac{dy}{dx}$ instead of $\dot{y}$~~

- In the post, actually $\dot{y}=\frac{dy}{dx}$. So,
- $$\int_{x_1}^{x_2}\frac{\partial f}{\partial \dot{y}}\frac{\partial \dot{y}}{\partial \alpha}\mathrm dx=\int_{x_1}^{x_2}\frac{\partial f}{\partial \dot{y}}\frac{\partial^2 y}{\partial x \partial \alpha}\mathrm dx$$
- In the equation, they just wrote $\frac{dy}{dx}$ instead of $\dot{y}$
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