已知涵数z=y sin(x+y),求dz

问题描述:

已知涵数z=y sin(x+y),求dz

z=ysin(x+y)
dz=dy*sin(x+y)+ysin'(x+y)
=sin(x+y)dy+ycos(x+y)(x+y)'
=sin(x+y)dy+ycos(x+y)(dx+dy)
=ycos(x+y)dx+[sin(x+y)+ycos(x+y)]dy.