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Math Help - Which method of integration is appropriate here?

  1. #1
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    Which method of integration is appropriate here?

    How would you integrate 1 / (v+v^3) ?

    I thought it would be [ 1 / (1+3v^2)] ln |v+v^3| by anti-differentiation but I don't think that is correct?

    Thanks!
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  2. #2
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    Quote Originally Posted by kselogatr View Post
    How would you integrate 1 / (v+v^3) ?

    I thought it would be [ 1 / (1+3v^2)] ln |v+v^3| by anti-differentiation but I don't think that is correct?

    Thanks!
    Use a partial fraction decomposition. If you need more help, please show all your work and say where you get stuck.

    (It is obvius that your answer is wrong. Differentiate it - Do you get back 1/(v + v^3) ....?)
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  3. #3
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    It appears that you tried to do this:



    so that you could use a u substitution.

    This is incorrect because you can only pull constants out of the integral, not functions.

    Like Mr F said, factorise the denominator then use partial fractions. You should find that your answer has a logarithm term and an arctangent term.
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