64
MÉMOIRE SUR LES INÉGALITÉS SÉCULAIRES
et l’équation (3) par
![{\displaystyle 2mdz-{\frac {2m(mdz+m'dz'+\ldots )}{1+m+m'+\ldots }},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/72a689f3fbb3b04fcc7b644261a327d30f6f9738)
si l’on multiplie pareillement la première des équations différentielles relatives à
par
![{\displaystyle 2m'dx'-{\frac {2m'(mdx+m'dx'+\ldots )}{1+m+m'+\ldots }},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/0a32650c41ef13d35e400502dcc401f255018a50)
la seconde par
![{\displaystyle 2m'dy'-{\frac {2m'(mdy+m'dy'+\ldots )}{1+m+m'+\ldots }},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/13f685b3a1d93a49017244b5b2d52472291dd004)
la troisième par
![{\displaystyle 2m'dz'-{\frac {2m'(mdz+m'dz'+\ldots )}{1+m+m'+\ldots }},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c48aab3b8b41ef48ed88c7d191f89005b8f75c75)
et ainsi du reste ; si l’on ajoute ensuite toutes ces équations et si l’on observe que
![{\displaystyle {\begin{aligned}0=&{\frac {\partial \lambda }{\partial x}}+{\frac {\partial \lambda }{\partial x'}}+{\frac {\partial \lambda }{\partial x''}}+\ldots ,\\0=&{\frac {\partial \lambda }{\partial y}}+{\frac {\partial \lambda }{\partial y'}}+{\frac {\partial \lambda }{\partial y''}}+\ldots ,\\0=&{\frac {\partial \lambda }{\partial z}}+{\frac {\partial \lambda }{\partial z'}}+{\frac {\partial \lambda }{\partial z''}}+\ldots ,\\r=&{\sqrt {x^{2}+y^{2}+z^{2}}},\\r'=&{\sqrt {x'^{2}+y'^{2}+z'^{2}}},\\\ldots &\ldots \ldots \ldots \ldots ,\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3c39fb21f214c31d72f14566f87bac355794963c)
on formera l’équation suivante :
![{\displaystyle {\begin{aligned}0=2m&{\frac {dxd^{2}x+dyd^{2}y+dzd^{2}z}{dt^{2}}}+2m'{\frac {dx'd^{2}x'+dy'd^{2}y'+dz'd^{2}z'}{dt^{2}}}+\ldots \\&-2{\frac {mdx+m'dx'+\ldots }{1+m+m'+\ldots }}\ {\frac {md^{2}x+m'd^{2}x'+\ldots }{dt^{2}}}\\&-2{\frac {mdy+m'dy'+\ldots }{1+m+m'+\ldots }}\ {\frac {md^{2}y+m'd^{2}y'+\ldots }{dt^{2}}}\\&-2{\frac {mdz+m'dz'+\ldots }{1+m+m'+\ldots }}\ {\frac {md^{2}z+m'd^{2}z'+\ldots }{dt^{2}}}\\&+2\left({\frac {mdr}{r^{2}}}+{\frac {m'dr'}{r'^{2}}}+\ldots \right)-2d\lambda .\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/1e19d1032552f95c7be33b5e9c3c95a3994a8134)