(a) The reference they were referring is : "Find a lower triangular matrix L, and a diagonal matrix D such that ". I don't see how this is relevant though.
Here's what I've done so far
From this, critical points are
Since
The Hessian matrix will be
So what else do I need to do here to solve this? (I can't find any similar examples from my textbook)
Also, can anyone show me how to prove part (b). I don't understand it...