70. En traitant cette équation comme nous l’avons fait (60) de l’équation (2), elle deviendra
71. De là on conclura d’abord l’équation
![{\displaystyle (13)\quad 0=\left\{{\begin{aligned}&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)'''+\ldots \right]X\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)'''+\ldots \right]Y\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} z}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} z'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} z''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} z'''}}\right)'''+\ldots \right]Z\end{aligned}}\right\}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/a7ac490b4a977c8b4b912df300cae3cb25dbb4cb)
![{\displaystyle +\left\{{\begin{aligned}&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)''-\ldots \right]X\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)'+\ldots \right]X'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)-\ldots \right]X''+\ldots \\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)''-\ldots \right]Y\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)'+\ldots \right]Y'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)-\ldots \right]Y''+\ldots \\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} z'}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} z''}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} z'''}}\right)''-\ldots \right]Z\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} z''}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} z'''}}\right)'+\ldots \right]Z'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} z'''}}\right)-\ldots \right]Z''+\ldots \\\\\end{aligned}}\right\}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/373821f08155a7ded21133be943c2af7f07551b7)
![{\displaystyle 0=\left\{{\begin{aligned}&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)'''+\ldots \right]X\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)'''+\ldots \right]Y\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} z}}\right)-\left({\frac {\operatorname {d} V}{\operatorname {d} z'}}\right)'+\left({\frac {\operatorname {d} V}{\operatorname {d} z''}}\right)''-\left({\frac {\operatorname {d} V}{\operatorname {d} z'''}}\right)'''+\ldots \right]Z\end{aligned}}\right\}.\quad (14)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/aa2f62b0fb81d9b35b73b17e89adff644b4e2f29)
