EIVSQVE VARIATIONE. 135 



Dcinde loco nn iterum fcribendo '^r&f^ fit 



vnde concludimus : 



dx ~(pr-±-a)i$fin.u 



x (1 — rcjj.wj V( pp — qq)' 



At ob xzz ??~%~ , forma differentialis ^p ita exhi- 

 beri poteft vt fit 



dx dp-j-d qcij.u drcof.w (pr-+-q)dujin.w _ — (pr- +-q)dQ)fin.(d 



x jc(i ~-rcoj.u) "T" 1 _rco/.w x ( i — r co/.cjj 2 — ( i — r coj. co) V( pp—qq) ' 



Quocirca erit 



~ [^ko/ruT- == - iL ^^^-+4'+# :of(0 +^cof.u. 



XVII I. Quodfi iam fbrmulas fuperiores ad P 

 et Q reduetas differentiemus, ad fequentes expreflio- 

 nes perueniemus t 



-\-dp(pp-\-ip qr-\-qq)-dq(2pq-{-ppr-\-qqr)- qdr(pp-qq) 



. 2(p-j-qr)*dP 



nn 



dp( 1 -rr)-\- rdq( i-rr)-\-qdr( 1 4-rr)-f zprdr - ^ff^ 



vnde cum differentialia dP et dQ dentur , bina 

 tantum trium elen entorum dp, dq et dr definiun- 

 tur , tertio quafi arbitrio noftro relicto. Verum 



n L. j -(pr+,?'ii(i!|)Jin. M 



UU UX (i-rcof.uly/ipp—qq) 



erit: d?-^^-. MxxCm^ et 



** X. — c t 1V1 lin • ^l (« -rcoJ*>) y (#>-_)]• 



Vel 



