dy/dx=3xy=xy^2dy/(3y+y^2)=xdx1/3*ln(y/3+y)=1/2*x^2+c1ln(y/3+y)=3/2*x^2+c2 (c2=3c1)y/3+y=e^(3/2*x^2+c2)=e^(3/2*x^2)*c (c=e^c2)所以y=3c*e^(3/2*x^2)/(1-c*e^(3/2*x^2)) 自己再看了化化吧.