Examples of Finite and Infinite Values for 0^∞ Indeterminate Form?

  • Thread starter Thread starter Mentallic
  • Start date Start date
  • Tags Tags
    Forms List
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
3 replies · 3K views
Homework Helper
Messages
3,802
Reaction score
95
Not so much a homework problem as a curiosity on my part. I chose to give a presentation recently on undefined numbers. With that, indeterminate's unsurprisingly found their way into my presentation.

After reading up on the list of indeterminate forms, I stumbled upon the form [tex]0^\infty[/tex] and for the life of my couldn't think of any examples in limits that have this form.

In my mind, I see such indeterminates as [tex]1^\infty[/tex] as trying to say
"multiplying 1 by itself repeatedly obviously still gives 1, but we're trying to do it so many times that it finally equals something other than 1".
Such an example would be e:

[tex]\lim_{x\rightarrow \infty}\left(1+\frac{1}{x}\right)^{x}[/tex]

Now a quick example of [tex]0^\infty[/tex] would be [tex]\lim_{x\rightarrow \infty}\left(\frac{1}{x}\right)^x[/tex]

but in a way, I see this as "enforcing" the answer zero since this limit tends to zero much faster than [tex]\lim_{x\rightarrow \infty}\frac{1}{x}[/tex] does.

So can anyone give me an example of such an indeterminate form that equals a finite, and possibly even infinite value.
 
Physics news on Phys.org


Where did you find the reference to [itex]0^\infty[/itex] as an indeterminate form? Off the top of my head, I can't think of a reason why this should be indeterminate.
 


Why is [itex]1^\infty[/itex] indeterminate?

Nevermind found it in the other thread.

x= 1^infinity is equivalent to ln(x)= infinity*ln(1)= infinity*0=0/1/infinity = 0/0

So is 0^infinity then equivalent to ln(x) = infinity*ln(0) = infinity*-infinity
 
Last edited: