Page:Annales de mathématiques pures et appliquées, 1822-1823, Tome 13.djvu/71

67

INDÉTERMINÉES.

$Const.=\left\{{\begin{aligned}&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{1}'+\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}''-\ldots \right]X_{1}\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}'+\ldots \right]X_{1}'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}-\ldots \right]X_{1}''+\ldots \\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{1}'+\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}''-\ldots \right]Y_{1}\\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}'+\ldots \right]Y_{1}'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}-\ldots \right]Y_{1}''+\ldots \\\\\end{aligned}}\right\}\,;$

d’où, en retranchant, on conclura, pour l’équation aux limites,

$0=\left\{{\begin{aligned}&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{1}'+\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}''-\ldots \right]X_{1}\\\\&\qquad +\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}'+\ldots \right]X_{1}'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{1}-\ldots \right]X_{1}''+\ldots \\\\-&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'}}\right)_{0}-\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{0}'+\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{0}''-\ldots \right]X_{0}\\\\&\qquad -\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x''}}\right)_{0}-\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{0}'+\ldots \right]X_{0}'-\left[\left({\frac {\operatorname {d} V}{\operatorname {d} x'''}}\right)_{0}-\ldots \right]X_{0}''-\ldots \\\\+&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{1}'+\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}''-\ldots \right]Y_{1}\\\\&\qquad +\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{1}-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}'+\ldots \right]Y_{1}'+\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{1}-\ldots \right]Y_{1}''+\ldots \\\\-&\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'}}\right)_{0}-\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{0}'+\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{0}''-\ldots \right]Y_{0}\\\\&\qquad -\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y''}}\right)_{0}-\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{0}'+\ldots \right]Y_{0}'-\left[\left({\frac {\operatorname {d} V}{\operatorname {d} y'''}}\right)_{0}-\ldots \right]Y_{0}''-\ldots \\\\\end{aligned}}\right\}\,;(7)$

63. Cela posé, si aucune condition n’a été prescrite relativement aux limites de l’intégrale ; c’est-à-dire, si les valeurs de $x,x',\ldots$$y,y',y'',\ldots$ peuvent être quelconques à ces limites, les fonctions $X,Y,$ et par suite les dérivées $X',Y',X'',Y'',\ldots$ devront, à ces mêmes limites, conserver toute leur indétermination et toute leur indépendance ; l’équation (7) ne pourra donc subsister alors gu’autant que les multiplicateurs de

$X_{0},X'_{0},X''_{0},\ldots Y_{0},Y'_{0},Y''_{0},\ldots$

$X_{1},X'_{1},X''_{1},\ldots Y_{1},Y'_{1},Y''_{1},\ldots$