\input epsf
\nopagenumbers
\magnification=\magstep1

\noindent {\bf Problem statement} Suppose that $t=f(u,v,w)$, with $f$
differentiable, and that $u=x-y$, $v=y-z$, and $w=z-x$.
 
\medskip

\noindent a) Use the Chain Rule to compute
$\displaystyle{\partial t\over\partial x}$.
 
\medskip

\noindent b) Show that $\displaystyle{\partial t\over\partial x} +
{\partial t\over\partial y} + {\partial t\over\partial z} = 0.$


\vfil\eject\end