$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}-6;}{-12x^{3}-65x^{2}-390x\phantom{;}-2340\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}-6\overline{\smash{)}-12x^{4}+7x^{3}\phantom{-;x^n}\phantom{-;x^n}-5\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}-6;}\underline{\phantom{;}12x^{4}-72x^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{\phantom{;}12x^{4}-72x^{3};}-65x^{3}\phantom{-;x^n}\phantom{-;x^n}-5\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-6-;x^n;}\underline{\phantom{;}65x^{3}-390x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;\phantom{;}65x^{3}-390x^{2}-;x^n;}-390x^{2}\phantom{-;x^n}-5\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-6-;x^n-;x^n;}\underline{\phantom{;}390x^{2}-2340x\phantom{;}\phantom{-;x^n}}\\\phantom{;;\phantom{;}390x^{2}-2340x\phantom{;}-;x^n-;x^n;}-2340x\phantom{;}-5\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}-6-;x^n-;x^n-;x^n;}\underline{\phantom{;}2340x\phantom{;}-14040\phantom{;}\phantom{;}}\\\phantom{;;;\phantom{;}2340x\phantom{;}-14040\phantom{;}\phantom{;}-;x^n-;x^n-;x^n;}-14045\phantom{;}\phantom{;}\\\end{array}$

$-12x^{3}-65x^{2}-390x-2340+\frac{-14045}{x-6}$