$\begin{array}{l}\phantom{\phantom{;}a\phantom{;}+3;}{\phantom{;}a^{3}-8a^{2}+26a\phantom{;}-78\phantom{;}\phantom{;}}\\\phantom{;}a\phantom{;}+3\overline{\smash{)}\phantom{;}a^{4}-5a^{3}+2a^{2}\phantom{-;x^n}-6\phantom{;}\phantom{;}}\\\phantom{\phantom{;}a\phantom{;}+3;}\underline{-a^{4}-3a^{3}\phantom{-;x^n}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-a^{4}-3a^{3};}-8a^{3}+2a^{2}\phantom{-;x^n}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}a\phantom{;}+3-;x^n;}\underline{\phantom{;}8a^{3}+24a^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{;\phantom{;}8a^{3}+24a^{2}-;x^n;}\phantom{;}26a^{2}\phantom{-;x^n}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}a\phantom{;}+3-;x^n-;x^n;}\underline{-26a^{2}-78a\phantom{;}\phantom{-;x^n}}\\\phantom{;;-26a^{2}-78a\phantom{;}-;x^n-;x^n;}-78a\phantom{;}-6\phantom{;}\phantom{;}\\\phantom{\phantom{;}a\phantom{;}+3-;x^n-;x^n-;x^n;}\underline{\phantom{;}78a\phantom{;}+234\phantom{;}\phantom{;}}\\\phantom{;;;\phantom{;}78a\phantom{;}+234\phantom{;}\phantom{;}-;x^n-;x^n-;x^n;}\phantom{;}228\phantom{;}\phantom{;}\\\end{array}$

$a^{3}-8a^{2}+26a-78+\frac{228}{a+3}$