( 286 ) 



or also 



V — Z civ civ 



'^-ry 



iv) 



d^ 



For {\-^y) Lh — we find according to (d), taking into account that 



dv 



Lb 

 {\ +x^ - = ^: 



V — 



(1 \y) Lb '-f = -— - i?(l-/V) if (.. + (/:). 



dy 



The vahie of — is found from 



dv 





from which follows : 



dy 1 



(it' x-\ 1 



f/(/) 



f/J' 



(IV dv 



With (y--6)'^ = — -^^seetj),and(y-è'^ = ---ji(l-^)(l \-,v[i) 

 dv ^-Vy dv x-\-i 



(.t' 4- f/--) : 1 -}-?/) (see (d)) this becomes: 



dy 

 at; 



1 



(.^ + l)(l+2/) 

 Hence 



dy 



(r-6)/-(l+^)A6-^ = 

 dv dv 





(/,? 



ip) 



(..■+l)(l+.V) 



9.l^(^ _ 



2/i(l -,i) r/(.. + r/) - (1 +y) |i(l— ,i) a(.^• + y) -f 



+ --T 1^(1 -i5) (l+xii) (l-2i?) (.^■^-r/)^ 



so that we find 



v— 6 2 1 



3 {l + yY 



{l + hy){l-i-y) + 



