144 
MEM OKI AS CIENTIFICAS I LITEli ARIAS 
18 
■ 
x~ — a^ 
■dx = 
dx 
= ^ t l y ' 
a + x 
a x 
VII. 
s/ 1+x 
- dx. 
Sustitucion aljebraica. 
Sea 
1 + x' 2 = z : 
dx dz 
x 
z 
d (x+z) 
z+z 
L ( x + J 1+x 2 
19. 
[ ± - - =± (— = ± L(x ± «/ x 2 -f a 2 ) 
J Vx 2 ±a 2 J z ^ 7 
VIII. 
f— J— 
J x/l“X“ 
d x. 
Sustitucion trigonometrical 
Sea 
x=sen t . • . d x = cos t d t: 
{ 1 a r cos t d t r a ± ± 
' — r=-dx= — - — — — = d t=t=arc sen x 
J \/ 1 — X 2 J cost J 
