Understanding Integration by Parts: Solving Tricky Integrals

In summary, Niles is having trouble following a step in his book involving integration. He thought it might involve integration by parts but that was not correct. After receiving guidance, he was able to successfully integrate the first term.
  • #1
Niles
1,866
0

Homework Statement


Hi

There is a step in my book, which I can't follow. It is the following

[tex]
\int_0^1 {w\left( {\frac{{d^2 u}}{{dx^2 }} - u + x} \right)dx} = \int_0^1 {\left( { - \frac{{dw}}{{dx}}\frac{{du}}{{dx}} - wu + xw} \right)dx} + \left[ {w\frac{{du}}{{dx}}} \right]_0^1
[/tex]

I thought they might be using integration by parts, but that doesn't seem to be correct. Any help is greatly appreciated.


Niles.
 
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  • #2
The first term, w u" is integrated by parts.

ehild
 
  • #3
I see, thanks!
 
  • #4
Does that answer your question?
If not, start to integrate the first term, w u'', by parts, & show us what you get.
 
  • #5
Yes, I got it. Thanks to both of you.Niles.
 

What is integration by parts?

Integration by parts is a method used in calculus to solve integrals that involve the product of two functions. It involves breaking down the integral into smaller, more manageable parts and using a specific formula to solve it.

When is integration by parts used?

Integration by parts is typically used when the integral involves a product of two functions, and there is no other method available to solve it. It is also used when the integral involves functions that are difficult to integrate using other methods.

How does integration by parts work?

Integration by parts involves using the formula ∫(u dv) = uv - ∫(v du), where u and v are functions and du and dv are their respective differentials. This formula is derived from the product rule of differentiation and is used to simplify the integral into smaller, easier-to-solve parts.

What are the steps to perform integration by parts?

The steps to perform integration by parts are: 1) Identify u and dv in the integral, 2) Calculate du and v using differentiation, 3) Substitute u, du, v, and dv into the formula ∫(u dv) = uv - ∫(v du), 4) Solve the integral on the right side, 5) Repeat the process until the integral is fully solved.

What are the common mistakes to avoid when using integration by parts?

Some common mistakes to avoid when using integration by parts are: 1) Choosing the wrong u and dv, 2) Forgetting to include the negative sign in the formula, 3) Not simplifying the integral after each iteration, 4) Forgetting to add the constant of integration at the end, 5) Using integration by parts when another method would be more efficient.

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