$\begin{array}{l}\phantom{\phantom{;}x\phantom{;}+3;}{\phantom{;}x^{2}-x\phantom{;}-2\phantom{;}\phantom{;}}\\\phantom{;}x\phantom{;}+3\overline{\smash{)}\phantom{;}x^{3}+2x^{2}-5x\phantom{;}+6\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x\phantom{;}+3;}\underline{-x^{3}-3x^{2}\phantom{-;x^n}\phantom{-;x^n}}\\\phantom{-x^{3}-3x^{2};}-x^{2}-5x\phantom{;}+6\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n;}\underline{\phantom{;}x^{2}+3x\phantom{;}\phantom{-;x^n}}\\\phantom{;\phantom{;}x^{2}+3x\phantom{;}-;x^n;}-2x\phantom{;}+6\phantom{;}\phantom{;}\\\phantom{\phantom{;}x\phantom{;}+3-;x^n-;x^n;}\underline{\phantom{;}2x\phantom{;}+6\phantom{;}\phantom{;}}\\\phantom{;;\phantom{;}2x\phantom{;}+6\phantom{;}\phantom{;}-;x^n-;x^n;}\phantom{;}12\phantom{;}\phantom{;}\\\end{array}$

$x^{2}-x-2+\frac{12}{x+3}$