$\begin{array}{l}\phantom{\phantom{;}x^{2}+2x\phantom{;}-1;}{\phantom{;}2x\phantom{;}+4\phantom{;}\phantom{;}}\\\phantom{;}x^{2}+2x\phantom{;}-1\overline{\smash{)}\phantom{;}2x^{3}+8x^{2}\phantom{-;x^n}+3\phantom{;}\phantom{;}}\\\phantom{\phantom{;}x^{2}+2x\phantom{;}-1;}\underline{-2x^{3}-4x^{2}+2x\phantom{;}\phantom{-;x^n}}\\\phantom{-2x^{3}-4x^{2}+2x\phantom{;};}\phantom{;}4x^{2}+2x\phantom{;}+3\phantom{;}\phantom{;}\\\phantom{\phantom{;}x^{2}+2x\phantom{;}-1-;x^n;}\underline{-4x^{2}-8x\phantom{;}+4\phantom{;}\phantom{;}}\\\phantom{;-4x^{2}-8x\phantom{;}+4\phantom{;}\phantom{;}-;x^n;}-6x\phantom{;}+7\phantom{;}\phantom{;}\\\end{array}$

$2x+4+\frac{-6x+7}{x^2+2x-1}$