先把前两项或者后两项放一起 ,
y'=(x^2)'lnxcosx+x^2(lnxcosx)'
=2xlnxcosx+x^2(lnx'cosx+lnxcosx')
=2xlnxcosx+x^2(1/xcosx-lnxsinx)
=2*x*ln(x)*cos(x)+x*cos(x)-x^2*ln(x)*sin(x) 先把前两项或者后两项放一起 ,
y'=(x^2)'lnxcosx+x^2(lnxcosx)'
=2xlnxcosx+x^2(lnx'cosx+lnxcosx')
=2xlnxcosx+x^2(1/xcosx-lnxsinx)
=2*x*ln(x)*cos(x)+x*cos(x)-x^2*ln(x)*sin(x)