$\displaystyle \int _0^ {1} {x^5 e^ {-x^3} dx}$ 의 값은?

• ①$\displaystyle \frac{1} {3} \left (1- \frac{2} {e} \right)$
• ②$\displaystyle - \frac{1} {3e}$
• ③$\displaystyle \frac{1} {3e}$
• ④$\displaystyle \frac{1} {3} \left (1+ \frac{2} {e} \right)$