Write the function in the form $y=f(u)$ and $u=g(x).$ Then find $\frac{dy}{dx}$ as a function of $x.$

$y=(\frac{\sqrt[\phantom{2}]{x}}{9}-4{)}^{-6}$

Write the function $u=g(x).$

$u=$

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Write the function $y=f(u).$

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ind $\frac{dy}{dx}$ as a function of $x$

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