# Proving a limit does not exist via delta epsilon

• Apr 28th 2010, 06:57 PM
blarkark
Proving a limit does not exist via delta epsilon
The limit of 1/(x^2-4) does not exist as x approaches 2- this makes sense since for any delta there are value of x that are arbitrarily 'close' to 2, thus making 1/(x^2-4) infinitely large, so no possible L will make 1/(x^2-4)-L<epsilon for a given epsilon. However, I don't know how to turn this into a formal statement. Any tips?
• Apr 28th 2010, 07:36 PM
dwsmith
Quote:

Originally Posted by blarkark
The limit of 1/(x^2-4) does not exist as x approaches 2- this makes sense since for any delta there are value of x that are arbitrarily 'close' to 2, thus making 1/(x^2-4) infinitely large, so no possible L will make 1/(x^2-4)-L<epsilon for a given epsilon. However, I don't know how to turn this into a formal statement. Any tips?

http://www.mathhelpforum.com/math-he...ta-proofs.html
• Apr 28th 2010, 10:31 PM
lovek323
I would be interested to see a worked proof for this example. I've never seen an example of how to prove that a limit doesn't exist using epsilon-delta.