December 4th, 2011, 06:45 PM  #1 
Member Joined: Nov 2011 Posts: 35 Thanks: 0  Positive and negative results
Hello, I have a limit: I've simplified it to such view: Wolframalpha shows, that there are 2 results: ±inf: http://www.wolframalpha.com/input/?i...%2C+x%3E0+%29 I can't understand, why does the result have ±? 
December 4th, 2011, 06:55 PM  #2 
Newbie Joined: Jul 2011 Posts: 5 Thanks: 1  Re: Positive and negative results
Wolfram has showed these results as the limit of x>0 has a different result depending which side you approach the limit from.

December 4th, 2011, 06:57 PM  #3 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  Re: Positive and negative results
We are given: We have then: 
December 4th, 2011, 06:57 PM  #4 
Member Joined: Nov 2011 Posts: 35 Thanks: 0  Re: Positive and negative results
So, can I just calculate it and leave the answer as: inf? Would it be right?

December 4th, 2011, 07:03 PM  #5 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 520 Math Focus: Calculus/ODEs  Re: Positive and negative results
I would simply state that the limit does not exist. There is a vertical asymptote of x = 0. On the left the function goes to negative infinity and on the right it goes to positive infinity, much like the function f(x) = 1/x.

December 4th, 2011, 07:04 PM  #6 
Member Joined: Nov 2011 Posts: 35 Thanks: 0  Re: Positive and negative results
Okay, thanks for the tip The question is solved.


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