Question

微分方程(x+y)(dx-dy)=dx+dy的通解

Answer 1

两边同除以dx,整理后得到dy/dx=(x+y-1)/(x+y+1),然后转化一下，d(x+y)/dx=2(x+y)/(x+y+1)。设u=x+y,得到du/dx=2u/(u+1)。以下略。。结果:x-y-ln(x+y)=c