$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}-3;}{\phantom{;}x^{2}-9x\phantom{;}-26\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}-3\overline{\smash{)}\phantom{;}x^{3}-12x^{2}+x\phantom{;}-42\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}-3;}\underline{-x^{3}+3x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-x^{3}+3x^{2};}-9x^{2}+x\phantom{;}-42\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n;}\underline{\phantom{;}9x^{2}-27x\phantom{;}\phantom{-;x^n}}\\\phantom{;\phantom{;}9x^{2}-27x\phantom{;}-;x^n;}-26x\phantom{;}-42\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-3-;x^n-;x^n;}\underline{\phantom{;}26x\phantom{;}-78\phantom{;}\phantom{;}}\\\phantom{;;\phantom{;}26x\phantom{;}-78\phantom{;}\phantom{;}-;x^n-;x^n;}-120\phantom{;}\phantom{;}\\\end{array}$

$x^{2}-9x-26+\frac{-120}{x-3}$