Typos/Inconsistencies

1. Page 104, Equation (5): < should read <=. And, there is an extra bracket after the third f.
2. Page 130, Prob 9: Tthis problem does not seem to make sense. Perhaps Hessian in (b) should read Jacobian. Also the Newton direction does not have an inverse. It appears that the Gauss-Newton method was intended.
3. Page 141, line 5: the solution should read 2/3(1 1)'
4. Page 236, Prob 4: There is no need for the "f convex" assumption. Coercivity is enough.
5. Page 214, Problem 11: This result fails unless the assumption `C is compact' is added to the hypotheses. (For example, choose C to be the whole space.)