Evaluate the following integrals.

$($a$)(7$ points$){\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}{x}^2{e}^{-5x^3}dx$

$($b$)$ points$){\displaystyle \underset{0}{\overset{5}{}}}{e}^x{x}^{2}dx$

$($c$)$ points$){\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{5x}{x^2+6x+8}dx$