How do you evaluate the integral xarcsec(x2)?

1 Answer
May 20, 2018

xarcsec(x2)dx

=12x2arcsec(x2)12ln(x2+x41)+C

Explanation:

xarcsec(x2)dx

=122xarcsec(x2)dx

After using y=x2 and 2xdx=dy transforms, this integral became

12arcsecydy

After using z=arcsecy, y=secz and dy=secztanzdz transforms, it became

12zsecztanzdz

=12zsecz12seczdz

=12zsecz12secz(secz+tanz)dzsecz+tanz

=12zsecz12ln(secz+tanz)+C

For y=secz, tanz must be equal to y21. Thus,

12yarcsecy12ln(y+y21)+C

=12x2arcsec(x2)12ln(x2+x41)+C