设y=xcosx;求(d^2y)/(dx^2)

Question

设y=xcosx;求(d^2y)/(dx^2)

Answer 1

都忘了差不多了.
y=xcosx
y/x=cosx
d(y/x)=dcosx=1?
(d^2y)/(dx^2)
=1/2*d(y/x)
=1/2?
我不确定了,好几年没接触数学了