∫(1,e)(1+lnx)dx/x
=∫(1,e)(1+lnx)dlnx
=∫(1,e)(1+lnx)d(lnx+1)
=1/2(lnx+1)^2+C |(1,e)
=1/2(lne+1)^2+C -1/2(ln1+1)^2-C
=1/2(1+1)^2+C-1/2(0+1)^2-C
=2+C-1/2-C
=3/2第二步是甚么意思∫dx/x=∫dlnx