两边对x求导：
y+xy'+1/x+y'/y=0
得：y'=-(y+1/x)/(x+1/y)设xy+lnx+lny=0,确定隐函数y=y(x),则dy/dx=?A y/xB-y/x Cy/(x^2y+x) D-y/(x^2y+x)请写过程化简一下就行了：y'=-(y+1/x)/(x+1/y)=-[(xy+1)/x]/[(xy+1)/y]=-y/x选B