x$.
                        <ol><li>Compute $Df$, the matrix derivative.</li>
    <li>We can think of $Df$ as being a function with some inputs and some outputs.  How many inputs and how many outputs does $Df$ have?</li>
    <li>Let $g(x,y)=Df(x,y)$.  Compute $Dg$ (which is the second derivative of $f$, or $D^2f$).  How does each entry in $D^2f$ relate to $f(x,y)$.</li></ol></div>
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<section>
  <h1>Par