Integration of an inverse function

In summary, the problem at hand is to integrate the function \frac{4}{x(x+3)}. The suggested method is to use partial fractions, by decomposing the function into the form \frac{A}{x}+\frac{B}{x+3}. This will make the integration process easier.
  • #1
iceman_ch
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Homework Statement



[tex]\int\frac{4}{x(x+3)}[/tex]

Homework Equations





The Attempt at a Solution



I can get to s certain point and I know I need to do substitution but, everytime I try a substitution it just creates a more difficult problem.

[tex]4\int(x^{-1}(x+3)^{-1})[/tex]

I've tried substitution x^-1 for U and using (x+3)^-1 for dv but, none of it works. If someone could give me a gentle nudge it would be appreciated.

Thanks
 
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  • #2
This problem is an ideal candidate for the method of "partial fractions".

Try decomposing [tex]\frac{1}{x(x+3)}[/tex] into the form [tex]\frac{A}{x}+\frac{B}{x+3}[/tex] where A and B are constants you need to determine.
 
  • #3
OH man so obvious. Your the man thank you so much. I havn't had a math class in over a year and now I'm taking diff eq. Bad idea you should definately keep them all together.
 
  • #4
And, when talking about functions, be careful to distinguish between "reciprocal" and "inverse" functions!
 

1. What is the inverse function?

The inverse function is a function that "undoes" the original function. In other words, if the original function takes an input x and produces an output y, the inverse function takes y as an input and produces x as the output. It can be thought of as a reflection of the original function over the line y=x.

2. Why is it important to integrate an inverse function?

Integrating an inverse function is important because it allows us to find the area under the curve of the original function. This is useful in many applications, such as calculating volumes, finding displacement, and solving differential equations.

3. How do you find the inverse function of a given function?

To find the inverse function, you can use the following steps:

  • Write the original function as y = f(x)
  • Switch the x and y variables, so it becomes x = f(y)
  • Solve for y in terms of x
  • The resulting function is the inverse function

4. What is the relationship between the derivative of a function and the integral of its inverse?

The derivative of a function and the integral of its inverse are inversely related. In other words, if the derivative of a function is f'(x), then the integral of its inverse is 1/f'(x). This relationship is known as the inverse rule of integration.

5. Can any function have an inverse function?

No, not all functions have an inverse function. For a function to have an inverse, it must be one-to-one, meaning that each input has a unique output. Additionally, the function must pass the horizontal line test, which means that no horizontal line should intersect the graph of the function more than once. If a function fails either of these conditions, it does not have an inverse function.

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