∫1x4 x4+14 dx=
13 (1+1x4)3/4+C
−13 (1+1x4)3/4+C
23 (1+1x4)3/4+C
−23 (1+1x4)3/4+C
∫x−51+1x44dx
1+1x4=t⇒−4.x−5dx=dt
−14∫1(t)14dt=−14t34(34)+C
=−13(1+1x4)34+C