Z=x+(y-1)arcsin根号下(x/y)
对x求导
Zx=1+(y-1)*1*(1/y)/根号下(1-x/y)
=1+(y-1)/y*根号下(1-x/y)
对y求导
Zy=arcsin根号下(x/y)+y*1*(-x/y^2)/根号下(1-x/y)
-(-x/y^2)/根号下(1-x/y)
=arcsin根号下(x/y)-x/y*根号下(1-x/y)+x/y^2*根号下(1-x/y)