对x偏导du/dx=ye^xy(cos(x+y^2))+e^xy(-sin(x+y^2)) 偏导的那个a打不出来对y偏导du/dy=xe^xy(cos(x+y^2))+e^xy(-sin(x+y^2))2ydu={ye^xy(cos(x+y^2))+e^xy(-sin(x+y^2))}dx+{xe^xy(cos(x+y^2))+e^xy(-sin(x+y^2))2y}...