po 



ob p ;:::: 1 _■ x -\- 2xx habebitur aequatîo canonica : 



ix — 1)^2/ -H 2 (1 — a; -h 2xx)y-\~x{x — 2) :=: 



cujus altéra forma erit : 



(.yy-{-^y-^ D^^ — ^(yy + y-^ iyx +y(iy-\-2^^=.Q. 



unde formulae directrices oriuntur : 



* — :y:)'-4-4>-t-» -(- Cl ^ — (^^ + 43, + ,),. • 



S. 4 8. Inclpiamus a valore cognito x ziz. , cui respondet 

 ^HZO, hincque séries valorum erit: 



a?=lO; ?/ = 0; a;=l2; «/ = — 14; a;:z=|^; etc. 

 Invertendo autem ordinem prodeunt sequentes valores : 



y-Q; x-Q; yz.~2; a;:=-2; y---%\ a— — |^; etc. 

 Sit nunc :r := 1 , cui respondet y -z=.\-, hinc séries ista a,' :n 1 ; 

 yrr|; :crr:|-;etc. At invertendo haec y nz | ; a; rz: I ; y^oc. 

 Superfluura foret a tertio valore xz^2, incipere , quia in praece- 

 dentibus jana continetur. 



§. 49. Sumamus nunc Q_-zz.x{x — 1) eritque : 



Rrr: — (a;— 1) (a; — 2), 



unde aequatio canonica erit: 



X ix — i') yy ■^- 2 (1 — a; -f- 2xx') y ^(x -- 1) (a? — 2) rz: 0, 



cujus altéra forma est: 



iyy-^ 4y-+- i^ XX — {yy -\- 2y -^ 3)a;-f- 2 (?/+ l) zz O. 

 Formulae ergo directrices erunt: 



*/ — — i(Lr^i±lHfI _ y sive i/ = ''—-^ 



y x{x — 1} "^ ^ xy 



