Let x ≥ 0, y ≥ 0, r > 1 and consider the non-linear system x′ = −x + rxy − x2 y′ = y(1 + y) (a) (2 points) Compute the Jacobian of this system. b) (4 points) The point (r−1, 1) is an equilibrium point of this system. Use supportive work to identify (r−1, 1) as sink/source, nodal/spiral, saddle point or center.