Analyze the stability of the disease model when = = 1, the point where the

Analyze the stability of the disease model when α = μ = 1, the point where the bifurcation occurs in Exercise 42.
Right at a bifurcation point, the stability theorem fails because the slope of the rate-of-change function at the equilibrium is exactly zero. In each of the following cases, check that the stability theorem fails, and then draw a phase-line diagram to find the stability.