Integral - u substitution with arctan

In summary, u substitution with arctan in integration involves rewriting the integral in terms of a new variable u and substituting the derivative of u with respect to x in the original integral. This allows for the evaluation of complex integrals involving trigonometric functions. The key steps to follow are to identify the appropriate substitution, find the derivative of u, substitute it in the integral, evaluate using the properties of arctan, and replace u with the original variable. Common mistakes to avoid include not finding the derivative of u, not substituting it in the integral, and forgetting to replace u in the final solution. U substitution with arctan is only applicable for integrals involving trigonometric functions.
  • #1
walksintoabar
1
0

Homework Statement


integral of 1/(x^2 + z^2)^(3/2) dx,
where z is a constant

Homework Equations



The Attempt at a Solution


I set u = arctan(x/z) so du = z/(x^2 + z^2) dx but now I'm honestly stuck.
 
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  • #2
You've got the correct substitution but you are thinking of this in a kind of convoluted way. Just put x=z*tan(u), so dx=z*sec(u)^2*du. Factor out a power of z and do the trig integral in u.
 
  • #3
[tex] x=z\sinh t [/tex]

is also a valid substitution.
 

What is the process of using u substitution with arctan in integration?

Using u substitution with arctan in integration involves rewriting the integral in terms of a new variable u, then finding the derivative of u with respect to x. This derivative is substituted in place of the dx in the original integral, and the resulting integral is evaluated using the properties of arctan.

Why is u substitution with arctan useful in integration?

U substitution with arctan is useful in integration because it allows us to simplify complex integrals involving trigonometric functions. By substituting in a new variable, we can often transform the integral into a simpler form that can be evaluated more easily.

What are the key steps to follow when using u substitution with arctan?

The key steps to follow when using u substitution with arctan are: identify the appropriate substitution, find the derivative of u with respect to x, substitute in the derivative and rewrite the integral in terms of u, evaluate the integral using the properties of arctan, and finally, replace u with the original variable to obtain the final solution.

What are some common mistakes to avoid when using u substitution with arctan?

Some common mistakes to avoid when using u substitution with arctan include forgetting to find the derivative of u with respect to x, not substituting the derivative in the integral, and forgetting to replace u with the original variable in the final solution. It is also important to ensure that the limits of integration are properly adjusted when using u substitution.

Can u substitution with arctan be used for all types of integrals?

No, u substitution with arctan is only applicable for integrals involving trigonometric functions, specifically those that can be rewritten in terms of arctan. Other types of integrals may require different substitution techniques.

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