dy/dx=y/[2(lny-x)]2lnydy-xdy=ydxlny^2dy=2xdy+ydxylny^2dy=2xydy+y^2dx1/2lny^2dy^2=d(xy^2)1/2d(y^2lny^2-y^2)=d(xy^2)y^2lny-y^2/2=xy^2+Cy^2lny-y^2/2-xy^2=C