7 In this problem, we use weak duality to prove Lemma 3.

a Show that Lemma 3 is equivalent to the following:

If the dual is feasible, then the primal is bounded. (Hint:

Do you remember, from plane geometry, what the contrapositive is?)

b Use weak duality to show the validity of the form of Lemma 3 given in part (a). (Hint: If the dual is feasible, then there must be a dual feasible point having a w-value of, say, wo. Now use weak duality to show that the primal is bounded.)