120 
MEMORIAS CIENTIFICAS I LITERARIAS 
d V=X d X 
. . v 2 x2 
f 1 1 -i/2ax-x if x 2 
/ u d v = — x 2 arc sen — / 1 — — / — - r l x 
J 2 2 r a 4./ y4a 2 — x 2 
Integrando por partes la nueva integral, se obtiene: 
y = — x 2 arc sen 
v 
2 a x — x 1 
— a 2 arc sen 
a 
2 a 
X V 4 a- — x 2 
O 
/- 
2 arc tg x 
1-fx 2 - 
d x = / x 2 arc tg x d (arc tg x) 
Sea 
u = x- 
d u = 2 x d x 
d v = arc tg x d (arc tg x) 
v = “ 2 " arc 2 tg x 
/ u d v = — x 2 arc 2 tg x — / x arc 2 tg x d x. 
Sea 
u = x . arc tg x 
d v = arc tg xdx 
1 xdx, 
du = -■ ■ , ~ + arc tg x d x 
ld-x 2 1 
v = x arc tg x — L ( 1-j-x 2 )T 
