z=(1+xy)^y=e^[(ln(1+xy))*y]取对数：lnz=y*ln(1+xy)求全微分：dz/z=(1/(1+xy))y*ydx+ln(1+xy)dy+(xy/(1+xy))dy=(1/(1+xy))y*ydx+[ln(1+xy)+(xy/(1+xy))]dy所以：dz/dy=[（1+xy）^y]*[ln(1+xy)+(xy/(1+xy))]...