int x*arcsec(x^2)*dx∫x⋅arcsec(x2)⋅dx
=1/2int 2x*arcsec(x^2)*dx12∫2x⋅arcsec(x2)⋅dx
After using y=x^2y=x2 and 2x*dx=dy2x⋅dx=dy transforms, this integral became
1/2int arcsecy*dy12∫arcsecy⋅dy
After using z=arcsecyz=arcsecy, y=seczy=secz and dy=secz*tanz*dzdy=secz⋅tanz⋅dz transforms, it became
1/2int z*secz*tanz*dz12∫z⋅secz⋅tanz⋅dz
=1/2z*secz-1/2int secz*dz12z⋅secz−12∫secz⋅dz
=1/2z*secz-1/2int (secz*(secz+tanz)*dz)/(secz+tanz)12z⋅secz−12∫secz⋅(secz+tanz)⋅dzsecz+tanz
=1/2z*secz-1/2ln(secz+tanz)+C12z⋅secz−12ln(secz+tanz)+C
For y=seczy=secz, tanztanz must be equal to sqrt(y^2-1)√y2−1. Thus,
1/2y*arcsecy-1/2ln(y+sqrt(y^2-1))+C12y⋅arcsecy−12ln(y+√y2−1)+C
=1/2x^2*arcsec(x^2)-1/2ln(x^2+sqrt(x^4-1))+C12x2⋅arcsec(x2)−12ln(x2+√x4−1)+C