I'm having difficulty plotting a vector field of a first-order system. I understand that I am supposed to select various points, "plug" them into the equations, and then plot the vector from the resulting point. But how do I know in which way the vector is pointing? Once I get the point from which the vector will originate, how do I decide in which direction to point that vector? Also, what do I do if I get a system such as dx/dt = x, dy/dt = 1? How would I plot dy/dt being that it is a constant?