Integrating a Fraction using the product rule

In summary, the conversation is about finding the integral of a complex expression using different methods. The person has attempted a solution using Integration by Parts, but it has resulted in a complex integral. Someone suggests using long division to simplify the expression, and also advises to write the tangent function as a fraction for easier simplification.
  • #1
sid777
1
0

Homework Statement


Find the integral of
gif.gif

This was the question. There is a way to do it by long division but I am confused with Long division. Instead I tried to do by the method below but I failed...

Homework Equations


None

The Attempt at a Solution


I thought maybe I could reduce the denominator to the power of -1 and then Integrate by Parts.
Like this
gif.gif

Is this correct? If no then what could I do to this integral. I would be very thankful if someone would post an answer...
 
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  • #2
Your attempt is valid, but you have created a more complex integral to solve. While there might be a way to solve this integral by dividing out to find the quotient, that too looks like it would create a messy integral to solve.
 
  • #3
Break it down into [tex]∫{\frac{x^3}{16xtanx+sinx}}dx+∫{\frac{56x^2sin^6x}{16xtanx+sinx}}dx[/tex]
Then try long division. If you can't do long division with polynomials, I would reccomend reading up on it. It creeps up quite a bit, and you're much better off knowing how to do it.

This is still going to be a nasty nasty integral, unless I'm missing something. I've not attempted it yet, but it seems like it might be easier that trying to to Integration by parts 20 times. Also With long division it may help to write ##{\tan{x}}## as ##{\frac{\sin{x}}{\cos{x}}}## and write the denominator as a fraction then simplify.
 

1. What is the product rule for integrating a fraction?

The product rule for integrating a fraction is a method used to integrate a fraction with two terms in the numerator and one term in the denominator. It involves breaking the fraction into two separate fractions and integrating them individually.

2. How do you apply the product rule for integrating a fraction?

To apply the product rule, you first need to identify the two terms in the numerator and the one term in the denominator. Then, you break the fraction into two separate fractions by multiplying the numerator and denominator by the term in the denominator. Finally, you integrate each fraction individually and add the results together.

3. What is the difference between the quotient rule and the product rule for integrating a fraction?

The quotient rule is used to integrate a fraction with two terms in the numerator and two terms in the denominator, while the product rule is used for fractions with two terms in the numerator and one term in the denominator. Additionally, the product rule involves breaking the fraction into two separate fractions, while the quotient rule does not.

4. Can the product rule be used for fractions with more than two terms in the numerator?

No, the product rule is specifically designed for fractions with two terms in the numerator and one term in the denominator. If the fraction has more than two terms in the numerator, a different integration method, such as partial fractions, may need to be used.

5. What are some common mistakes when using the product rule for integrating a fraction?

One common mistake is not correctly breaking the fraction into two separate fractions. It is important to multiply the numerator and denominator by the term in the denominator to create two separate fractions. Another mistake is not simplifying the fractions before integrating them, which can lead to incorrect results. It is also important to be careful with signs when breaking the fraction into two separate fractions.

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