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\centerline{\bf Math.~125 Quizz \#3}
\centerline{September 15, 1998}
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Write an equation for the tangent line to the curve
$$y={{8}\over{x^2+7}}$$
at the point on  the curve for which $x=1$.
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Find all the points on the curve 
$$y={{4x}\over{x^2+1}}$$
where the tangent line is parallel to the line $y=x$.
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Write a formula for $f^\prime(x)$ if $f(x)$ is given by the formula
$$f(x)={{{4-x^2+2x^4}}\over{x^2-9}}$$

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