∫xlnx(x2+1)2(1)Đặt{u=xlnxdv=1(x2+1)2⇒{du=(lnx+1)dxv=ln(x2+1)2
(1)=xlnx.ln(x2+1)2+c−∫ln(x2+1)2.(lnx+1)dx
=xlnx.ln(x2+1)2−c+H
H=∫2ln(x2+1).(lnx+1)dx
=∫[2ln(x2+1)lnx]dx+∫2ln(x2+1)dx
=2∫ln(x+x2+1)dx+2∫ln(x2+1)dx
=2(x+x2+1)ln(x+x2+1)−(x+x2+1)+2(x2+1)ln(x2+1)−(x2+1)+c
" Công thức ∫ln(x)=xlnx−x+c "
(1)=.....................