[tex]\bf \cfrac{d}{dx}\left[ \cfrac{x}{11}-\cfrac{11}{x} \right]\implies
\cfrac{d}{dx}\left[ \cfrac{x}{11} \right]-\cfrac{d}{dx}\left[\cfrac{11}{x} \right]
\\\\\\
\cfrac{1}{11}\cdot \cfrac{d}{dx}\left[x \right]-11\cdot \cfrac{d}{dx}\left[\cfrac{1}{x} \right]
\implies
\cfrac{1}{11}\cdot 1~~-~~11\cdot \cfrac{d}{dx}[x^{-1}]
\\\\\\
\cfrac{1}{11}~~-~~11\cdot -x^{-2}\implies \cfrac{1}{11}+\cfrac{11}{x^2}
\implies
\cfrac{x^2+121}{11x^2}[/tex]
