Proof of Theorem on Differentiability and Lebesque Integral

In summary, he gives the theorem in one of his other books, and the proof for the converse is in Real and Complex Analysis.
  • #1
Nusc
760
2
Hello,


I was wondering where I can find a proof to the following theorem:

If F is differentiable at every pt. of [a,b] and if F' is lebesque on [a,b] then

F(x) = int(f,dt,a,x) a<=x<=b.


And the converse.


He gives the theorem are page 324 and a reference in his bibliography. I was wondering where I detailed proof for this theorem.
 
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  • #2
He proves that in his Real & Complex Analysis book. It's Theorem 8.21 on page 169 of the first edition.
 
  • #3
Thank you dearly.
 
  • #4
Hey morphism,

do you know where I can find the proofs for the theorems 11.23 (a), (d), (e), (f), 11.24(b), 11.26, 11.27, 11.29, and 11.32 extended to Lebesgue integrals of complex functions?
 
  • #5
Have you tried to prove them yourself? They easily follow from their real-valued analogues.
 
  • #6
He just gives the converse to

If F is differentiable at every pt. of [a,b] and if F' is lebesque on [a,b] then

F(x) = int(f,dt,a,x) a<=x<=b.

Where can I find the proof for this?
 
  • #7
Sorry, the actual theorem is:

If f in L on [a,b] and F(x)=int(f,t,a,x) (a<=x<=b) then F'(x)=f(x) almost everywhere on [a,b].

and he uses strictly eveywhere for continuity, why is this>
 
  • #8
I'm not sure that I understand what it is you're asking.

Nusc said:
He just gives the converse to

If F is differentiable at every pt. of [a,b] and if F' is lebesque on [a,b] then

F(x) = int(f,dt,a,x) a<=x<=b.

Where can I find the proof for this?
Like I said, this is in one of his other books (with your typos corrected!), Real and Complex Analysis.

Nusc said:
Sorry, the actual theorem is:

If f in L on [a,b] and F(x)=int(f,t,a,x) (a<=x<=b) then F'(x)=f(x) almost everywhere on [a,b].

and he uses strictly eveywhere for continuity, why is this>
Where is this from? And continuity of what is being used?
 
  • #9
It was from baby rudin on page 324. I can only find the proof for the converse in Real and Complex Analysis.
 

Related to Proof of Theorem on Differentiability and Lebesque Integral

1. What is the meaning of differentiability and Lebesque integral in mathematics?

Differentiability refers to the property of a function where its derivative exists at every point in its domain. Lebesque integral, on the other hand, is a type of integral used to calculate the area under a curve for more complex functions that cannot be integrated using traditional methods.

2. What is the importance of proving the theorem on differentiability and Lebesque integral?

The proof of this theorem is important because it provides a rigorous and logical justification for the use of these concepts in mathematics. It also helps to establish the validity and reliability of these concepts in various mathematical applications.

3. What are the key components of the proof of the theorem on differentiability and Lebesque integral?

The proof typically involves using the fundamental theorem of calculus, the definition of differentiability, and the properties of the Lebesque integral. It also requires a thorough understanding of calculus and real analysis.

4. Are there any real-life applications of this theorem?

Yes, this theorem has a wide range of applications in various fields such as physics, engineering, economics, and statistics. For example, it can be used to analyze the rate of change of a physical system, calculate the area under a curve in economic models, or estimate the probability of an event occurring in statistics.

5. Are there any limitations or assumptions in the proof of this theorem?

Like any mathematical proof, there may be certain assumptions or limitations in the proof of this theorem. For instance, it may only be applicable to certain types of functions or may require certain conditions to be met. It is important to carefully examine the assumptions and limitations before applying the theorem in any specific context.

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