Convergence and Integrability of Function Series in Measure Spaces and Applications to Series Expansion Integrals
1) Let $(X,\Sigma,\mu)$ be a measure space and for each n suppose that $f_{n}:X\rightarrow \mathbb{R} $ is an integrable function such that $\sum_{n=1}^{\infty } \int |f_{n}|du$ is convergent.
Prove that $\sum_{n=1}^{\infty } f_{n}$ converges almost everywhere to an integrable function and that
$$\int \sum_{n=1}^{\infty}f_{n} du=\sum_{n=1}^{\infty}\int f_{n}du.$$
2) Use problem 1) to show that
$$ \int_{0}^{1}\sin(x)\ln(x)dx=\sum_{n=1}^{\infty} \frac{(-1)^n}{(2n)(2n)!}. $$
Elviegem
41
Answer
Answers can only be viewed under the following conditions:
- The questioner was satisfied with and accepted the answer, or
- The answer was evaluated as being 100% correct by the judge.
1 Attachment
Poincare
133
The answer is accepted.
Join Matchmaticians Affiliate Marketing
Program to earn up to a 50% commission on every question that your affiliated users ask or answer.
- answered
- 395 views
- $20.00
Related Questions
- Banach fixed-point theorem and the map $Tf(x)=\int_0^x f(s)ds $ on $C[0,1]$
- Spot my mistake and fix it so that it matches with the correct answer. The problem is calculus based.
- real analysis
- Solve the attached problem
- A complex Analysis problem
- Prove that $\frac{d \lambda}{d \mu} = \frac{d \lambda}{d \nu} \frac{d \nu}{d \mu}$ for $\sigma$-finite measures $\mu,\nu, \lambda$.
- Integral of $\arctan x$
- real analysis