Maximizing Integration Efficiency: Long Division vs Partial Fractions

In summary, the conversation discusses different approaches to solving the integral ∫(2x+1)/(x²+2x+1)(x²+x+1). The suggested method is to use partial fractions rather than long division. It is also mentioned that long division should only be used when the degree of the numerator is larger than the denominator, or when they are equal.
  • #1
Cacophony
41
0

Homework Statement


∫(2x+1)/(x²+2x+1)(x²+x+1)


Homework Equations


none


The Attempt at a Solution


I've foiled this out to look like:

∫(2x+1)/(x^4+3x³+4x²+3x+1)

I'm trying long division here but it's getting really ugly really fast. Should I foil this out in the first place or should I use a different approach?
 
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  • #2
I would try a different approach.

Look at the denominator and see if it can be factored rather than multiplied together.
 
  • #3
Cacophony said:
I've foiled this out to look like:

∫(2x+1)/(x^4+3x³+4x²+3x+1)

I'm trying long division here but it's getting really ugly really fast. Should I foil this out in the first place or should I use a different approach?
Why would you try long division? You are dividing something "smaller" into something "bigger". It is as if you are suggesting that to evaluate [itex]\frac{7}{584}[/itex] you divide 584 by 7.

Have you considered using partial fractions to split the integral into two?
 
  • #4
Definitely do partial fractions. The only time you do long division is when the degree on top is bigger than the bottom.
 
  • #5
iRaid said:
Definitely do partial fractions. The only time you do long division is when the degree on top is bigger than the bottom.
Or when the degrees are equal.
 

FAQ: Maximizing Integration Efficiency: Long Division vs Partial Fractions

1. What is long division in the context of integrals?

Long division in the context of integrals is a technique used to simplify complex integrals by breaking them down into smaller, more manageable parts. It involves using polynomial long division to divide the integrand by a simpler polynomial, which can then be integrated more easily.

2. When should I use long division when integrating?

Long division is typically used when the integrand is a rational function, meaning it is a ratio of two polynomials. This method is especially useful when the degree of the numerator is equal to or greater than the degree of the denominator. It can also be used when the integrand contains a quadratic expression.

3. How do I perform long division when integrating?

To perform long division when integrating, follow these steps:

  1. Write the integrand in the form of a fraction, with the numerator as the dividend and the denominator as the divisor.
  2. Arrange the terms of the dividend and divisor in descending order of degree.
  3. Divide the first term of the dividend by the first term of the divisor, and write the result as the first term of the quotient.
  4. Multiply the divisor by the first term of the quotient and subtract the result from the dividend.
  5. Repeat the process until the remainder is smaller than the divisor, and write the remainder as the final term of the quotient.

4. What are the benefits of using long division when integrating?

Using long division when integrating can greatly simplify the process and make it more manageable. It can also help identify patterns and relationships between terms, making it easier to find the antiderivative. Additionally, it can be used to find the partial fraction decomposition of a rational function, which is useful for solving more complex integrals.

5. Are there any limitations to using long division in integration?

Yes, there are some limitations to using long division in integration. This method is only applicable to rational functions, so it cannot be used for other types of integrals. It also may not work for all rational functions, as some may require other techniques such as substitution or integration by parts. Additionally, it can be time-consuming and may not always result in a simpler integral.

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