INtegration by substitution followed by parts:

In summary, the conversation is about finding the integral of (x tan^2 x) using trig identities and integration by parts. The person asking for help has tried using trig identities, but is still struggling and asks for further guidance. The other person suggests using a specific trig identity and integrating by parts, and reminds them to follow the forum guidelines for homework questions. The conversation ends with a final reminder to show their work so they can receive further assistance.
  • #1
O.J.
199
0
... of (x tan^2 x). i don't know how to do it. pls help
 
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  • #2
Well, what have you tried? This is clearly homework! Try writing tanx in terms of sinx and cosx.
 
  • #3
i tried that. i even tried using trig identities for the expansion of tan^2 but i got no where. I am lost...
 
  • #4
any ideas?
 
  • #5
this is by-parts integration because you have two functions multiplied by each other.
But before you do that you should use a trig identity (think of an identity which will give you an easily integratable trig function).
 
  • #7
Good work though :P
 
  • #8
O.J. said:
any ideas?

Hint: Do you know an identity for tan2x in terms of, say, sec2x?

Try using this then integrate by parts. Post your work so we can help you.
 

FAQ: INtegration by substitution followed by parts:

1. What is integration by substitution followed by parts?

Integration by substitution followed by parts is a method of integrating a function that involves breaking it down into smaller parts and using substitution to simplify the integration process.

2. When is integration by substitution followed by parts used?

This method is typically used when the integrand (the function being integrated) can be broken down into two smaller functions, one of which can be easily integrated by substitution and the other by parts.

3. How do you use integration by substitution followed by parts?

To use this method, first identify the two functions that make up the integrand. Then, use substitution to simplify one of the functions, and use integration by parts to integrate the other function. Finally, combine the two results to solve the original integral.

4. What are the benefits of using integration by substitution followed by parts?

This method can be used to solve integrals that would be difficult or impossible to solve using other methods. It also allows for the integration of more complex functions by breaking them down into smaller, more manageable parts.

5. Are there any limitations to integration by substitution followed by parts?

While this method is useful for many integrals, it may not work for all types of functions. Some integrals may require other methods, such as trigonometric substitution or partial fractions, to solve. It is important to consider all available integration techniques when approaching a difficult integral.

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