we have the following:
[tex]y=\frac{9}{x^4}-\frac{4}{x}[/tex]
derivate:
[tex]\begin{gathered} y^{\prime}=9\frac{d}{dx}(\frac{1}{x^4})-4\frac{d}{dx}(\frac{1}{x}) \\ y^{\prime}=9\cdot(\frac{-6}{x^5})-4(\frac{-1}{x^2}) \\ y^{\prime}=-\frac{36}{x^5}+\frac{4}{x^2} \end{gathered}[/tex]
therefore, the correct answer is first option
