>>800
y'=2+3(x/y)、x/y=tとおくと、xt'=2+(3/t)-t、
→ -∫t/(t^2-2t-3) dt=∫dx/x、log|x^4*(t+1)(t-3)^3|=C、(x+y)(3x-y)=c、3x^2+2xy-y^2=c