- #1

fabiancillo

- 27

- 1

Prove that the sequence $f_n : [0,1] \longrightarrow{\mathbb{R}}$ defined by $f_n(t)=t^n(1-t)$ converges uniformly to the null function in [0,1]Thanks

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- MHB
- Thread starter fabiancillo
- Start date

In summary, to prove the uniform convergence of the sequence $f_n(t)=t^n(1-t)$ on $[0,1]$, we can use the Weierstrass M-test by choosing $M_n=1$ and showing that $\sum_{n=1}^{\infty} 1$ converges. This will then prove that the sequence converges uniformly to the null function on $[0,1]$.

- #1

fabiancillo

- 27

- 1

Prove that the sequence $f_n : [0,1] \longrightarrow{\mathbb{R}}$ defined by $f_n(t)=t^n(1-t)$ converges uniformly to the null function in [0,1]Thanks

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- #2

Evgeny.Makarov

Gold Member

MHB

- 2,436

- 4

Prove that $\max_{t\in[0,1]}f_n(t)\to0$ when $n\to\infty$.

- #3

soloenergy

- 64

- 0

One approach to proving this is to use the Weierstrass M-test. This theorem states that if there exists a sequence of positive numbers $M_n$ such that $|f_n(t)| \leq M_n$ for all $n$ and for all $t \in [0,1]$, and if $\sum_{n=1}^{\infty} M_n$ converges, then the series $\sum_{n=1}^{\infty} f_n(t)$ converges uniformly on $[0,1]$.

In this case, we can choose $M_n = 1$ for all $n$, since $|f_n(t)| \leq 1$ for all $t \in [0,1]$. And since $\sum_{n=1}^{\infty} 1$ is a convergent series, by the Weierstrass M-test, we can conclude that the sequence $f_n$ converges uniformly to the null function on $[0,1]$.

I hope this helps with your exercise. Let me know if you have any other questions or if you need further clarification on any of the steps. Good luck!

Uniform convergence is a type of convergence where the rate of convergence is independent of the point in the domain. In other words, the function converges to the same limit at the same rate at every point in the domain.

Pointwise convergence is a type of convergence where the function converges to a different limit at each point in the domain. This means that the rate of convergence can vary at different points. Uniform convergence, on the other hand, has a consistent rate of convergence at every point in the domain.

Proving uniform convergence is important because it guarantees that the limit of the sequence of functions is the same function as the limit of the sequence of their values. This allows us to make conclusions about the behavior of the function as a whole, rather than just at specific points.

There are several methods for proving uniform convergence, including the Cauchy criterion, the Weierstrass M-test, and the Dini's theorem. These methods involve analyzing the behavior of the sequence of functions and their corresponding limits.

Uniform convergence has many applications in mathematics, including in the study of series, integrals, and differential equations. It also plays a crucial role in the development of numerical methods and in the analysis of functions and their properties.

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