Let's say that we have the differential equation dy dx, or the derivative of y with respect to x, is equal to negative x over y. Let's say we don't know how to find the solutions to this, but we at least want to get a sense of what the solutions might look like. And to do that, what we could do is we could look at a coordinate plane. So, let me draw some axes here. So, let me draw a relatively straight line. Alright, so that's my y-axis, and this is my x-axis. Let me do draw, let me mark this as one, that's two, that's negative one, negative two, one, two, negative one, and negative two.