Answer: 0
Step-by-step explanation:
[tex]\frac{x^{3}e^{-x}}{5}[/tex]
This could be written as
[tex]\frac{x^{3} }{5e^{-x} }[/tex]
Applying L'H rule and differentiating 3 times , we have
[tex]\frac{6}{5e^{x} }[/tex]
taking the limit as x goes to infinity , we have
0