# Homework Help: Deceptive uniform convergence question

1. Mar 31, 2013

### Zondrina

1. The problem statement, all variables and given/known data

http://gyazo.com/55eaace8994d246974ef750ebeb36069

2. Relevant equations

Theorem III :
http://gyazo.com/af2dfeb33d3382430d39f275268c15b1

3. The attempt at a solution

At first this question had me jumping to a wrong conclusion.

Upon closer inspection I see the sequence converges to 1 as n goes to infinity for |x|<1. The sequence converges to 0 as n goes to infinity for |x|≥1. Hence the sequence is not uniformly convergent over the whole real line.

If we restrict the domain of x to (-1,1) or (-∞,-1] U [1,∞), then we can observe uniform convergence over each interval respectively.

The question isn't too clear about what it's asking for, but that's my take.

2. Mar 31, 2013

### Dick

I think you are supposed to conclude that given the theorem, if the $f_n$ are continuous and the limit function is not continuous, then the convergence can't be uniform. And I don't think they converge uniformly on (-1,1) either or any of the other intervals you are talking about. If you think they do please let me know why.

3. Apr 1, 2013

### Zondrina

I see, I think i understand how the theorem and the question relate. I never did check the convergence on the intervals though so I suppose I shouldn't have assumed.

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