Question

limit of x^3*e^(-x) when x goes to -infinity

Answer 1

\[ \large \lim_{x\to-\infty}x^3e^{-x}=\lim_{x\to-\infty}\frac{x^3}{e^x}=0 \]

Answer 2

i think the answer is minus infinity, can you explain how you did the last move and got zero ? Thanks !

Answer 3

well
\[ \large a^{-n}=\frac{1}{a^n} \]

Answer 4

u r right, sorry, it is \(-\infty\)

Answer 5

so how you know it ? can you explain ? i can't figure this one out

Answer 6

http://www.wolframalpha.com/input/?i=limit+x-%3E-infinity+of+x%5E3*e%5E%28-x%29+&dataset=
click show steps....