^uae fumtis quadrads reducetur ad iftarn formam: 



J&ft vero 



xxX -\-y y Y — B (x X +y y) -\- C [x* + J'*) 



, -i-D (A-*4-y) -i-E(x'+y) 



Kincqi-e pernenietur ad hanc aequationem 



§. 77. Sumamus nunc vt fupra conflantem A ita 

 Yt pofito 



y — o fiat jfnyt et X zzK -B -i- C k k -{- D k* E k' 



et aequatiT intej^ralis induet hanc formam: 



B r ■■ - f- '\/i-4_rf 4-f-v4)-| -Drx-y-vfx3:-)--v> ) -t-iE3C *'V*:+^ a3r3'VXY 



5j±_£ii, qnae aliquanto fimplicior euadit fi vtrin- 

 qiie fubtrahamus C: erit enim 



Bfyx»4-'V'v>4- aCy xy \-Hr)3C r ^ytr x-j-ty^ + j^E x* y* Z^ aX>VX Y B^ 



• :: (x« — j»; — kk 



quae cgregie conuenit cum integrali fupra §. 72. exhibito. 



§. 78. Hic cafus notatu dignus fe offert, dum B — o, 

 tum autem aequatio diffcrentialis ita fe habebit: 



a V(C-f-Dxx -(-£>:♦} j)'V(C-(-D>:y -+-£>*•) 



^cuius ergo integiale per conflantem A exprefium erit 



C''.-4-}-vt^^T)X3C3 > 3'(rx-t--v-v)-f-aE3t*-' ^: 3 JC> VX Y ^ 



IToc autem cafu integratio non ita determinari poteft, rt 

 -pofito j m o fiat x-^k, quia integrale pofterioris mem- 

 bri hoc catei manifefto ^bit in infiaitumj quam obrem 



alio 



