设z=ycosu+usiny，其中u=f(x，y)为可导函数，则等于：A.-ysinu+2usinyB.-ysinu+cosu+2usiny+ucos

发布时间：2021-02-15 04:14:22

1.[]设z=ycosu+usiny，其中u=f(x，y)为可导函数，则等于：A.-ysinu+2usiny B.-ysinu+cosu+2usiny+ucosy C.(2usiny-ysinu)f′ D.cosu+ucosy+(2usiny-ysinu)f′ABCD