LOS METODOS DE INTEGRA CION 
101 
16. / x cos x d x = x sen x — f sen x d x 
= x sen x + cos x 
(Duhamel, I, 429) 
_ „ r , r sen ax 1 r , 
1 * . /x cos a x d x = x / / sen a x d x 
J J a a J 
x sen a x cos a x 
■ + —7 
18. / cos x L sen x d x. 
u = L sen x . * d u = cot x 
d v = cos x d x . • . v — — sen x 
y = — sen x L sen x — sen x . 
19. / sen x L cos x d x=cos x L cos x-i-cos x. 
20. f x . arc sen x d x . 
u=arc sen x . ■ . du = 
d x 
i/f 
v d = x d x 
V = — X- 
— x^ arc sen x^ — R ( 
2 4 j yi 
1 r x 2 dx 
4 J l/l — X s 
1 2 1 1 , T 
- x‘ 2 arc sen x + — arc cos x — x j/ 1 
(Bertrand, 10) 
