10. Consider a growth process with discounting, modelled by a natural exponential function. a) Show that with any value function, V(t)=Kef(t), and a given continuous discount rate, i, the first-order condition for the present discounted value of V(t),A(t), to reach its maximum is that the rate of growth of V(t),r, be equal to i. b) Show that the second-order condition for a maximum really amounts to the rate of growth of V(t) be strictly decreasing with time