When taking the limit at infinity, is this allowed?

find_the_fun
Messages
147
Reaction score
0
In this video of Laplace transforms the equation $$\lim_{t \to \infty}\frac{te^{-st}}{-s}$$ is said to be 0. I'm not sure I agree with the reasoning. It says it's because $$e^t$$ grows faster than $$t$$; can you treat infinity like that? For example could you say $$\lim_{x \to \infty}\frac{x}{x^2}=0$$? I thought it was undefined because obviously $$\frac{infty}{infty}$$ is undefined.
 
Last edited:
on Phys.org
The form $$\frac{\infty}{\infty}$$ is indeterminate...to allay your concerns, apply L'Hôpital's Rule. :D
 
MarkFL said:
The form $$\frac{\infty}{\infty}$$ is indeterminate...to allay your concerns, apply L'Hôpital's Rule. :D

Maybe the video was aluding to L'Hôpital's Rule when it said $$e^t$$ grows faster than $$t$$.

By the way, according to here $$\frac{\infty}{\infty}$$ is indeterminate.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
3
Views
2K
Replies
15
Views
11K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 2 ·
Replies
2
Views
4K