The given function f is given by:
[tex]f(x)=\frac{1}{(x^5-7x+6)^8}[/tex][tex]\begin{gathered} \text{ Let }u\text{ be a function given by:} \\ u(x)=x^5-7x+6 \end{gathered}[/tex]Therefore,
[tex]\frac{du}{dx}=5x^4-7[/tex]and
[tex]f(x)=\frac{1}{u^8}[/tex]Therefore,
[tex]f^{\prime}(x)=\frac{df}{du}\times\frac{du}{dx}[/tex]Since f = 1/u⁸, it follows that:
[tex]\frac{df}{du}=-\frac{8}{u^9}[/tex]Therefore,
[tex]\begin{gathered} f^{\prime}(x)=-\frac{8}{u^9}\times(5x^4-7) \\ =-\frac{8}{(x^5-7x+6)^9}\times(5x^4-7) \end{gathered}[/tex]Therefore,
[tex]f^{\prime}(x)=\frac{8(7-5x^4)}{(x^5-7x+6)^9}[/tex].