Uniformly convergent sequence proof

In summary: Since f_n(x) converges uniformly to f(x), for any ε>0 there exists N≥1 such that for all n≥N and all x in [0,1]:|f_n(x) - f(x)| < ln(1+ε) Using this, we can show that for all ε>0 there exists N≥1 such that for all n≥N and all x in [0,1]:|e^{f_n(x)} - e^{f(x)}| < e^{f(x)} ln(1+ε) Thus, the sequence e^{f_n(x)} converges uniformly to e^{f(x)} on [0,1].
  • #1
function22
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Homework Statement



Let [tex]f_n(x)[/tex] be a sequence of functions that converges uniformly to f(x) on the interval [0, 1]. Show that the sequence [tex]e^{f_n(x)}[/tex] also converges uniformly to [tex]e^{f(x)}[/tex] on [0,1].

Homework Equations



The definition of uniform convergence.

The Attempt at a Solution



I tried to use the definition of uniform convergence to prove this, so I need to show that for all ε>0 there exists N≥1 for all n≥N for all x in [0,1] [tex]|e^{f_n(x)}-e^{f(x)}| < ε[/tex]. I tried to prove this from the fact that [tex]f_n(x)[/tex] converges uniformly to f(x) but I kept getting stuck and I'm not sure how to do this problem now. Can anyone help me please?
 
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  • #2
function22 said:

Homework Statement



Let [tex]f_n(x)[/tex] be a sequence of functions that converges uniformly to f(x) on the interval [0, 1]. Show that the sequence [tex]e^{f_n(x)}[/tex] also converges uniformly to [tex]e^{f(x)}[/tex] on [0,1].

Homework Equations



The definition of uniform convergence.

The Attempt at a Solution



I tried to use the definition of uniform convergence to prove this, so I need to show that for all ε>0 there exists N≥1 for all n≥N for all x in [0,1] [tex]|e^{f_n(x)}-e^{f(x)}| < ε[/tex]. I tried to prove this from the fact that [tex]f_n(x)[/tex] converges uniformly to f(x) but I kept getting stuck and I'm not sure how to do this problem now. Can anyone help me please?

This seems like a promising first step:

[tex]|e^{f_n(x)} - e^{f(x)}| = e^{f(x)} |e^{f_n(x)-f(x)} - 1|[/tex]
 

FAQ: Uniformly convergent sequence proof

What is a uniformly convergent sequence?

A uniformly convergent sequence is a sequence of functions that converges to a limiting function at the same rate in every part of its domain.

How is a uniformly convergent sequence different from a pointwise convergent sequence?

In a pointwise convergent sequence, the rate of convergence may vary at different points in the domain. In a uniformly convergent sequence, the rate of convergence is the same everywhere in the domain.

What is the importance of proving that a sequence is uniformly convergent?

Proving that a sequence is uniformly convergent is important because it guarantees that the limiting function is continuous, and the sequence of functions can be integrated or differentiated term by term.

What is the standard method for proving uniform convergence of a sequence?

The standard method for proving uniform convergence of a sequence is to use the Weierstrass M-test, which states that if a sequence of functions can be bounded by a convergent series of numbers, then the sequence is uniformly convergent.

Can a sequence be uniformly convergent but not pointwise convergent?

Yes, a sequence can be uniformly convergent but not pointwise convergent. This means that the limiting function is continuous, but the pointwise limit does not exist at some points in the domain.

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