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\centerline
{
\bf ``QUIZ'' for Oct. 1, 2009
}
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{\bf NAME:} (print!) $\underline
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{\quad \bf Section:}
$\underline{\quad\quad\quad}$

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{\bf E-MAIL ADDRESS:} (print!) 
$\underline
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{\bf 1.} 
Find ${{\partial f} \over {\partial r}}$
and ${{\partial f} \over {\partial s}}$ as 
{\bf functions of $r$ and $s$ }, if
$$
f(x,y)= x^2 +2xy^2+ 2y^3 \quad,
$$
and the variables are related by $x=r+2s$ and $y=3r+2s$.
You do not need to simplify!


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{\bf 2.} 
Find ${{\partial z} \over {\partial x}}$
and ${{\partial z} \over {\partial y}}$ if 
$$
x^2+y^2+z^2=5xyz+1 \quad .
$$


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