u'v=-(2lnx)/x
u'=-(2lnx)/x^2
du=-(2lnxdx)/x^2
u=-2 int lnx*1/x^2 *dx=(u=lnx, du=dx/x; dv=dx/x^2, v=-1/x)=-2(-lnx/x +int dx/x^2)=-2(-lnx/x - 1/x)+C =
= 2(ln x/x + 1/x) + C