Integration of a reciprocal function

In summary, the conversation involves evaluating the integral of (4-x2)-3/2 using integration by parts and u-replacement. The person asking for help is looking for hints on how to start and has already tried using various substitutions. Another person suggests using a trig substitution by letting x=2sin(\theta). Eventually, the person is able to solve the integral and get the final answer of x/(4(4-x2)1/2).
  • #1
Shawn Garsed
50
0

Homework Statement


Evaulate the integral of (4-x2)-3/2.

Homework Equations


integration by parts
u-replacement

The Attempt at a Solution


Too long to write it all down, but I used the aforementioned equations. Basically, I'd like somebody to give me a hint about how or where to start, since everything I tried so far hasn't worked.
 
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  • #2
Is this an indefinite integral?
 
  • #3
yes, it is
 
  • #5
Shawn Garsed said:

Homework Statement


Evaulate the integral of (4-x2)-3/2.

Homework Equations


integration by parts
u-replacement

The Attempt at a Solution


Too long to write it all down, but I used the aforementioned equations. Basically, I'd like somebody to give me a hint about how or where to start, since everything I tried so far hasn't worked.
What did you use for the substitution? What did you use for the parts of the integration by parts?

We can give much better help if you show us what you've done. Besides that, it's part of the rules for Homework help in this Forum.
 
  • #6
Yes, that's what I meant by u-replacement. Sorry if that wasn't clear.
 
  • #7
Generaly speaking, integrals that involve roots of squares call out for a trig substitution. What happens if you let [itex]x= 2 sin(\theta)[/itex]?
 
  • #8
I've used 4-x2, (4-x2)-1/2 and (4-x2)
1/2
as a substitution.
 
  • #9
Thanks HallsofIvy, I got it now. It's x/(4(4-x2)1/2).
 

Related to Integration of a reciprocal function

1. How do you integrate a reciprocal function?

To integrate a reciprocal function, you need to use the power rule for integration. This means that you need to raise the function to the power of -1 and then add 1 to the power. For example, if your function is f(x) = 1/x, then you would raise it to the power of -1 and add 1, resulting in f(x) = x^-1 + 1. Then you can apply the power rule, which states that the integral of x^n is (x^n+1)/n+1. In this case, the integral of x^-1 would be (x^-1+1)/-1+1, which simplifies to -x^-1 + C.

2. What is the inverse function of a reciprocal function?

The inverse function of a reciprocal function is simply the reciprocal function itself. This means that if your original function is f(x) = 1/x, then the inverse function would be f^-1(x) = x. This is because when you plug in x into the inverse function, you would get 1/x, which is the original function.

3. Can you use substitution to integrate a reciprocal function?

Yes, substitution can be used to integrate a reciprocal function. This method involves substituting a variable for the function inside the integral, and then using the chain rule to solve for the integral. For example, if your function is f(x) = 1/x, you could substitute u = 1/x, which would result in du = -1/x^2 dx. Then you can solve for the integral using the new variable u.

4. What are the limits of integration for a reciprocal function?

The limits of integration for a reciprocal function depend on the specific problem or context in which the function is being used. In general, the limits of integration would be the values of x for which the function is defined. For example, if your function is f(x) = 1/x, the limits of integration could be any values of x where x ≠ 0.

5. How is integration of a reciprocal function used in real life?

Integration of a reciprocal function has many real-life applications, such as in physics and engineering. One example is in the calculation of work done by a variable force. The work done is equal to the integral of the reciprocal of the force with respect to the displacement. Reciprocal functions are also commonly used in economic and financial analysis, such as in the calculation of marginal utility and elasticity of demand.

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