$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}+3;}{\phantom{;}3x^{2}-9x\phantom{;}+17\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}+3\overline{\smash{)}\phantom{;}3x^{3}\phantom{-;x^n}-10x\phantom{;}+9\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}+3;}\underline{-3x^{3}-9x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-3x^{3}-9x^{2};}-9x^{2}-10x\phantom{;}+9\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n;}\underline{\phantom{;}9x^{2}+27x\phantom{;}\phantom{-;x^n}}\\\phantom{;\phantom{;}9x^{2}+27x\phantom{;}-;x^n;}\phantom{;}17x\phantom{;}+9\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n-;x^n;}\underline{-17x\phantom{;}-51\phantom{;}\phantom{;}}\\\phantom{;;-17x\phantom{;}-51\phantom{;}\phantom{;}-;x^n-;x^n;}-42\phantom{;}\phantom{;}\\\end{array}$

$3x^{2}-9x+17+\frac{-42}{x+3}$