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\centerline{\bf Math.~125 Quizz \#4}
\centerline{September 22, 1998}
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Write an equation for the tangent line to the curve
$$x^4+y^4=9$$
at the point on  the curve $(2,1)$.
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For what values of $x$ is the tangent line to the curve
$$y=\sin(x^2)$$
horizontal?

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