42 METHODVS NOVA CALCVLVM 



ducerc licet, ita vt in omnibus eadem formula(^) 

 occurrat. Quum enim dx(j^j) fit difFerentialc 

 formiilae 'i^) fumta iola x variabili , erit per con- 

 fuetan integralium redudionem : 



/ P -/ .V (ii^) = P («) - fd X (tl) (ij ) , 

 fimili modo quia </4_ii2_) eft dffcrentiale formu- 

 lae (/-/j-j) habebimus llatim lianc rcduclioncm 



nuac vero per praecedentem reduflionem fit 



f-iii ) ( j-'.T )=(S) ^lf ^-/^^-^t'-..*) (ii) 



iicque omnino liabebimus 



atque nunc fatis perfpicuum ef^ , fequcntem formu- 

 lam intcgralcm ita rcdudum iri : 



ac fi infuper talis formula adeffet, foret : 



-ii'/.ni'r)+f'^xr^.){ti). 



14. Qiiodfi nunc has formulas rcdudas fubfti- 

 tuamus in exprcdioiic variationis quacfitac, formulae 

 /Z</.v, tu:ii hacc varlatio non fuhim formuhs con- 

 ilibit iatciirahbus , fcd ctiam contiutbit partcs ab- 



folu- 



