The integral is given as,
I= ∫ x sec 2 xdx
Use integration by parts. Consider sec 2 x as second function and x as the first function.
I= ∫ x sec 2 xdx =x ∫ sec 2 xdx − ∫ ( d dx x ∫ sec 2 xdx )dx =xtanx− ∫ tanxdx I=xtanx+log| cosx |+C
Thus, the integration of ∫ x sec 2 xdx is xtanx+log| cosx |+C.