- Number 2 and 17 were in general well done.

- Number 5 was not a success.  Most people didn't understand I think what
they had to prove, especially in 5 a).  Please look at solutions for
this one.

- For number 9, I was surprised that a lot of people submitted some kind
of graphic proof.  This is clearely not the right approach for a proof.  A
proof should always stand on its own without the drawings.  Please look at
solutions for this one too.

- For number 10, some people argued that x^* was in the interior of C.
This might not be true.  For example, the function f(x)=x^2 has
derivatives defined everywhere on R, and is convex.  If we minimize this
function on the interval [1,2] (notice that [1,2] is a convex set and that
the derivative is defined on this set), then the minimum occurs at x^*=1.
Notice that at x*, f'(x^*)>0 and f'(x^*).(x-x*)>=0 for all x in the
interval [1,2].

- Number 19 had to be done following the proof in the book for each
theorem and looking in general where the A-G inequality was used and what
conditions were implied for equality.  Please refer again to the
solutions.

- A lot of people left some problems untried.  Please try to write what you
know even if the solution is not complete.  I usually give some points for
this.  I can only give 0 for blank solutions.

Good luck for the next assignment.
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