Can i solve using partial fractions?

In summary, the conversation discusses how to solve the integral ∫(x+1)/(x2+2x+3)dx by using partial fractions. The attempted solution involves using u-substitution, but it is suggested that completing the square in the denominator would be a more efficient method. The conversation also mentions the use of complex numbers in the solution. A resource for understanding the concept of completing the square is provided.
  • #1
johann1301
217
1

Homework Statement



∫(x+1)/(x2+2x+3)dx

The Attempt at a Solution



This problem was under partial fractions in my book. I solved it using u-substitution where u=x2+2x+3, but i can't see how it can be solved using partial fractions?

can it?
 
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  • #2
Yeah, you could, but it's a lot of extra work.

Hint: Complete the square in the denominator.
 
  • #3
(x^2+2x+3)=(x+3)(x+1)?
 
  • #4
no, i see that's not right..
 
  • #5
I get that (x^2+2x+3) = (-1-√2i)(-1+√2i).
 
  • #6
but their complex... will this work?
 
  • #7
sorry, (x^2+2x+3) = (x+1+√2i)(x+1-√2i).
 
  • #8

Related to Can i solve using partial fractions?

1. What are partial fractions?

Partial fractions are a mathematical technique used to decompose a complex rational function into smaller, simpler fractions.

2. When should I use partial fractions?

Partial fractions are commonly used in integration problems, where they can simplify the integration process. They can also be used in solving linear differential equations and in finding the inverse Laplace transform.

3. How do I solve using partial fractions?

To solve using partial fractions, you must first factor the denominator of the rational function into linear and irreducible quadratic factors. Then, you set up a system of equations using the coefficients of the fractions and solve for the unknowns.

4. Are there any restrictions when using partial fractions?

Yes, there are a few restrictions to keep in mind when using partial fractions. The factors in the denominator must be distinct, the degree of the numerator must be less than the degree of the denominator, and all the coefficients must be real numbers.

5. Can I use partial fractions for improper rational functions?

Yes, partial fractions can also be used for improper rational functions, where the degree of the numerator is greater than or equal to the degree of the denominator. In these cases, the partial fractions will include a polynomial term in addition to the simpler fractions.

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