LOS M^TODOS DE INTEGKACION 
121 
Sustituyendo i reduciendo, resulta: 
( x — -i- arc tg x J arc tg x — L V 1 x 2 
9. 
earc tg x 
(l+x*)!- 
d x . 
Sea 
(Gregory, 257) 
u = e arc ^ x 
pare tg x 
du= — dx 
d v 
dx 
l-^hr 
J (X-3+1) — 
v/(l+X 2 )« 
V = 
X 
x/l+X 2 
y = 
x e arc tg x C x . e arc tg x 
3 
d x 
(1+x2)t j (1 + x 2 )T 
Sea 
u = e arct gx 
pare tg x 
' du »"l+- dx 
d v = 
x d x 
(1+xs )4 
v/14 X 2 
