求解dx/(x+t)=dy/(-y+t)=dt
问题描述：
求解dx/(x+t)=dy/(-y+t)=dt
答
∵dx/(x+t)=dy/(-y+t)=dt==>dx/(x+t)=dt,dy/(-y+t)=dt==>dx-xdt=tdt,dy+ydt=tdt==>e^(-t)dx-xe^(-t)dt=te^(-t)dt,e^tdy+ye^tdt=te^tdt==>d(xe^(-t))=d(-(t+1)e^(-t)),d(ye^t)=d((t-1)e^t) ==>xe^(-t)=C1-(t+1)e^(-t)...