For the system
x = x + 2y
y = 3x + y
(i) Establish the fixed point.
(ii) Derive the equations for the two isoclines and establish the vector of forces.
(iii) Derive the equation for the stable and unstable arms.
(iv) Take a point on the stable arm for x =2, and show on a spread- sheet that the trajectory does indeed move towards the origin along the arm. Plot the trajectory from point (2,- 2), and show that this trajectory moves away from the stable arm.