分步积分
∫[1,4] (1n x/√x)*dx
=2∫[1,4] 1n xd√x
=2√xlnx[1,4] -2∫[1,4] √xd1n x
=8ln2-2∫[1,4] √x/xd x
=8ln2-2∫[1,4] d√x
=8ln2-4√x[1,4]
=8ln2-4