$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}+3;}{\phantom{;}x^{3}-4x^{2}+13x\phantom{;}-42\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}+3\overline{\smash{)}\phantom{;}x^{4}-x^{3}+x^{2}-3x\phantom{;}-6\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}+3;}\underline{-x^{4}-3x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-x^{4}-3x^{3};}-4x^{3}+x^{2}-3x\phantom{;}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n;}\underline{\phantom{;}4x^{3}+12x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;\phantom{;}4x^{3}+12x^{2}-;x^n;}\phantom{;}13x^{2}-3x\phantom{;}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n-;x^n;}\underline{-13x^{2}-39x\phantom{;}\phantom{-;x^n}}\\\phantom{;;-13x^{2}-39x\phantom{;}-;x^n-;x^n;}-42x\phantom{;}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n-;x^n-;x^n;}\underline{\phantom{;}42x\phantom{;}+126\phantom{;}\phantom{;}}\\\phantom{;;;\phantom{;}42x\phantom{;}+126\phantom{;}\phantom{;}-;x^n-;x^n-;x^n;}\phantom{;}120\phantom{;}\phantom{;}\\\end{array}$

$x^{3}-4x^{2}+13x-42+\frac{120}{x+3}$