Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2002/iii/paper-56/2/d/solution

The global curve is a homoclinic connection to the lower positive equilibrium, which is the saddle equilibrium created at the saddle-node bifurcation. Near on the side , place it at
tangent to at the double-zero point. The stable periodic orbit occupies the strip and approaches the saddle equilibrium on the upper boundary. The dashed curve in the two-parameter figure indicates this local placement; its drawn numerical coefficient is schematic, not a computed global-bifurcation formula.
This placement is consistent with the supplied normal form. Its centre equilibrium has a supercritical Hopf bifurcation, and its saddle equilibrium has negative trace on the relevant loop branch, allowing a stable periodic orbit to disappear in the saddle equilibrium loop. No global-curve calculation is required here.

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