How to integrate int -1/(x^2 +1)^2 dx

In summary, to solve the integral -1/(x^2 +1)^2, we can use a substitution method by letting u = x^2 + 1 and applying the power rule for integrals. There is no specific shortcut or trick for solving this type of integral, but understanding substitution can make it easier. The domain of this integral is all real numbers except for x = ±i, where i is the imaginary unit. Integration by parts is not applicable in this case. It is possible to graph the function given by this integral, but there will be a discontinuity at x = ±i.
  • #1
cscott
782
1

Homework Statement



Find the following intergral...

Homework Equations



[tex]\int{\frac{-1}{(x^2+1)^2}dx}[/tex]

The Attempt at a Solution



I can't get anywhere with this... any hints?
 
Last edited:
Physics news on Phys.org
  • #2
sorry rushed the problem and did it wrong
 
Last edited:
  • #3
hint:

[tex] \frac{d}{{dx}}{\arctan{x}} = \frac{1}{x^2 +1} [/tex]
 
Last edited:
  • #4
Try adding and subtracting x^2 in the numerator.
 
  • #5
Make the substitution [itex] x=\tan t [/itex]. You'll eventually get [itex] \int \cos^2 t \ dt [/itex] which is easy to do.

Daniel.
 

1. How do I solve the integral -1/(x^2 +1)^2?

Solving integrals involving fractions can often be tricky, but in this case, we can use a substitution method. Let u = x^2 + 1, then du = 2x dx. Substituting this into the integral, we get -1/2 * ∫ du/u^2. This can be solved using the power rule for integrals, giving us the final answer of -1/2u + C. Remember to substitute back in for u to get the final answer in terms of x.

2. Is there a shortcut or trick to solving this integral?

Unfortunately, there is no specific shortcut or trick to solving this integral. However, understanding and applying substitution, as shown in the previous answer, can often make solving integrals involving fractions easier.

3. What is the domain of this integral?

The domain of this integral is all real numbers except for x = ±i, where i is the imaginary unit. This is because the original function has a singularity at these points, making the integral undefined.

4. Can I use integration by parts to solve this integral?

No, integration by parts is not applicable in this case. Integration by parts is typically used when the integral contains a product of two functions, but in this case, we only have a single function -1/(x^2 +1)^2.

5. Is it possible to graph the function given by this integral?

Yes, it is possible to graph the function y = -1/(x^2 +1)^2, which is the antiderivative of the integrand. However, keep in mind that the graph will have a discontinuity at x = ±i due to the singularity of the original function at these points.

Similar threads

  • Calculus and Beyond Homework Help
Replies
3
Views
335
  • Calculus and Beyond Homework Help
Replies
7
Views
692
  • Calculus and Beyond Homework Help
Replies
5
Views
1K
  • Calculus and Beyond Homework Help
2
Replies
54
Views
8K
  • Calculus and Beyond Homework Help
Replies
22
Views
1K
  • Calculus and Beyond Homework Help
Replies
11
Views
686
  • Calculus and Beyond Homework Help
Replies
9
Views
718
  • Calculus and Beyond Homework Help
Replies
15
Views
776
  • Calculus and Beyond Homework Help
Replies
8
Views
754
  • Calculus and Beyond Homework Help
Replies
10
Views
419
Back
Top