218 MEMORIAS CIENTfFICAS I LITERARIAS 
da ^ dx dii T 2 L x 
=2L xdL x = 2L x — = z 
y X dX X 
1. 
y = (t-f x 2 ) earctg* (CATALAN 123) 
dy r 2x 
L y=e arctgA- L (1 * 2 ); -2l=j e arctg* _ -|-L(1 + **) 
U i 1 ~\~x 2 
^arc tg . 
1 -\-x 2 
e arct e* / 2a; L (1-fa; 2 ) \ 
1 +*> e " c,8 i+E + -T+?- 
2. = arc sen (x y/i— a 2 a — .r 2 ) (Niewenglowski, 73) 
=arc sen x-f-arc sen a (N.° 29, C, b) 
dy- 
dx 
e e 
dij—e 
3. 
y=e 
e 
. . i x doe 
