Integration by partial fractions?

In summary, the conversation is about the integration of a complex fraction, specifically \int \frac{3x + 32}{x^{2}-16x + 64}dx. The person is struggling with factoring the denominator and is unsure of what to do next. They mention that they may need to use polynomial long division if the numerator has a higher degree than the denominator. However, in this case, the numerator is not of a higher order. The conversation concludes with a suggestion to complete the square in the numerator.
  • #1
James2
35
0
Whoa, this here is kicking me hard! Okay, so I've got everything pretty well down until... stuff like... [tex]\int \frac{3x + 32}{x^{2}-16x + 64}dx[/tex]

So, I get how to factor the denominator, but then what? The above won't factor... Also, I read that if the degree of the numerator is higher than the denominator I got to do polynomial long division... I need a review of polynomial long division; Lol.
 
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  • #2
James2 said:
Whoa, this here is kicking me hard! Okay, so I've got everything pretty well down until... stuff like... [tex]\int \frac{3x + 32}{x^{2}-16x + 64}dx[/tex]

So, I get how to factor the denominator, but then what? The above won't factor... Also, I read that if the degree of the numerator is higher than the denominator I got to do polynomial long division... I need a review of polynomial long division; Lol.
But the numerator is not higher order than the denominator and:$$\frac{3x + 32}{x^{2}-16x + 64}=\frac{3x+32}{(x-8)^2}$$See also:
http://www.math.ucdavis.edu/~kouba/CalcTwoDIRECTORY/partialfracdirectory/PartialFrac.html
 
  • #3
x^2-16x+64=(x-8)^2
3x+32=3(x-8)+56
 
  • #4
... oh yes, and complete the square in the numerator.
Thanks lurflurf. The example does not seem to illustrate the following comments does it?
 

1. What is integration by partial fractions?

Integration by partial fractions is a method used in calculus to simplify and solve integrals involving rational functions. It involves breaking down a rational function into smaller, simpler fractions that can be more easily integrated.

2. When is integration by partial fractions used?

This method is used when an integral involves a rational function, which is a function with a polynomial in the numerator and denominator. In these cases, integration by partial fractions can help to simplify the integral and make it easier to solve.

3. How does integration by partial fractions work?

The basic steps for integration by partial fractions are as follows:

  1. Factor the denominator of the rational function into linear or irreducible quadratic factors.
  2. Express the rational function as a sum of simpler fractions with each factor in the denominator.
  3. Determine the unknown coefficients of the fractions by equating the numerators of the original function to the sum of the numerators of the simpler fractions.
  4. Integrate the simpler fractions using basic integration rules.
  5. Combine the individual integrals to get the final solution.

4. What are some common types of integrals that can be solved using integration by partial fractions?

Integration by partial fractions is commonly used to solve integrals involving rational functions with distinct linear factors, repeated linear factors, and irreducible quadratic factors. It is also useful for solving integrals with complex numbers in the denominator or when using trigonometric substitutions.

5. Are there any limitations to using integration by partial fractions?

Integration by partial fractions can only be used when the integral involves a rational function. It also requires the denominator to be factored into distinct linear or irreducible quadratic factors. If the denominator cannot be factored or if it contains higher degree polynomials, this method cannot be used.

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