Question

y=cos^2x*lnx 二阶导数

Answer 1

(uv)''

=(u'v+uv')'

=u''+2u'v'+v''

令

u=cos^2x

v=lnx

u'=-2sinxcosx=-sin2x

v'=1/x

u''=-2cos2x

v''=-1/x^2

代入后即可.