1. The bifurcation diagram for an autonomous differential equation y' = f(y) is shown below. The solid parts correspond to stable equilibria and the dashed part is for unstable ones. f(y) has a parameter c, and chang- ing the value of that parameter changes the behavior of the system, as shown. %3D 8 -15 (a) Sketch the phase lines when c = -20, c = -5, c = 0, and c = 10. (Hint: consider how your phase lines appear on/in the graph above.) (b) Sketch the corresponding graphs of y vs. t for each of the choices of c listed above.