(a) Suppose a = b = 1 in the Gompertz differential equation(7). Since the DE is autonomous, use the phase portrait concept of Section 2.1 to sketch representative solution curves corresponding to the cases P₀ > e and 0 < P₀ < e.

(b) Suppose a = 1, b = -1 in (7). Use a new phase portrait to sketch representative solution curves corresponding to the cases P₀ > e^-1 and 0 < P₀ < e^-1.