100 
MEMORIAS CIENTIFICAS I LITERARIAS 
i-x s Ls 
(Appell, 51) 
13 / x 3 L x d x . 
u=L x 
d v=x 3 d x 
du = 
v = 
d x 
x 
y = 
— x 4 Lx 
4 
r 1 , d x 1 , T 1 
J T x - — =X sLx -T6^ 
14. /.Lx; x n d x. 
u = L x . • . d u 
d v = x n d x . • . v = 
X n + i T 1 r 
y = "i . . i L x — y x u d x 
4 “ ““ 16 
(Bertrand, 9) 
- ^ x 
x 
X n + 1 
n + 1 
n + 1 
n + 1 
x n+1 
(l 
i 
-) 
15. / x sen x d x. 
n + 1 V - ■ ■ n-|- 1 ) 
(Briot, II, 504) 
u — x . * . d u = d x 
d v = senxdx v= — cosx 
y= — x cos x + y d sen x = — x cos ix + sen x. 
j 
(Moigno, II, 15) 
