已知z=sin(3x+y), 则dz=( )
选项:
A:3cos(3x+y)dx+cos(3x+y)dy;
B:cos(3x+y)dx+cos(3x+y)dy;
C:3cos(3x+y)+cos(3x+y);
D:3cos(3x+y)dx+sin(3x+y)dy
发布时间:2024-04-02 15:51:04