Сократите дробь: (x^8+x^13)/(x^-4+x).

\[\frac{x^{8} + x^{13}}{x^{- 4} + x} = \frac{x^{8}\left( 1 + x^{5} \right)}{x^{- 4}\left( 1 + x^{5} \right)} = x^{12}\]