216 MEMORIAS CIENTIFICAS I L1TERARIAS 
e 2X —l r (e 2x —Y 
T : L 
e 2X i 1/ j 
(e 2 x -\-\) e 2X . 2 — (e 2 x — 1) e 2 x . 2 
(e 2 x \) 2 -{-{e 2 x — 1 ) 2 e z x_^ e —? x 
dx. 
14. 
d arc cos 
b-\-a cos x 
a -\-b cos x 
(Williamson, 24) 
(b-—a 2 ) sen x d x, /6-)-acos*\ 2 
(a-\-b cos x) 2 V ' a-\-b cos a) 
(a 2 — b 2 ) sen x d x 
= V £z± ,/* 
cos ( a-\-b cos x ) 2 — ( b-\-a cos x) 2 a-\-b cos .v 
15. y = L j / \A+*4V*- * _ ] t V ^ 1 x +V' 1 ' 
\/l+* — V 7 ! - ^ \/ 1 +--v ~\/ 1 — x 
_i ^ (y/i-MV i -^O 2 
-n 
( i+y/i — ® 2 ) — 1 £ 
(^q= : (l+y/l-^ 2 )- ~ ) d x ~-= o-—l =• d X 
x ) 2 
16. j/— ai^ctg 
V 7 1-l-ar 2 — 1 
+ arc tg 
1 — x 2 
x 
