ﬁrst order PDE http://imgur.com/d36NZcK Here is the question In case the image doesn't load http://imgur.com/d36NZcK 2. Relevant equations 3. The attempt at a solution The general solution is just the sum of homogeneous solution and any exact solution. What I got was f(x^2-y^2)e^(-2)+ye^(x). I'm not sure about my answer and have no idea what to do with the initial condition. As u(x,y)is a dependent variable of x and y, how can it be on a 2-dimensional curve.