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Integration problem (check my work)

  • Thread starter Aerosion
  • Start date
  • #1
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Homework Statement



(integrate)((cos(x)/(7*sin(x)+21))

Homework Equations





The Attempt at a Solution



I actually solved it, but I fear it might be wrong (that and my calculator says a different answer).

Anyway, I factored a 1/7 out of the equation, to make the equation (1/7)(integrate)((cos(x)/(sin(x)+21)). I subsituted (sin(x)+21) for u, and made du cos(x).

This made the integral (1/u), which I turned into ln(u). Now I had (1/7)*ln(u). I just rewrote that into ln(u)/7, then subbed sin(x)+21 into u, making the answer ln(sin(x)+21)/7.

Did I do anything wrong here?
 

Answers and Replies

  • #2
236
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if i understood what you wrote it should be like this after factoring the 1/7
(1/7)(integrate)((cos(x)/(sin(x)+3))
 
  • #3
HallsofIvy
Science Advisor
Homework Helper
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Yes. The denominator is 7sin(x)+ 21= 7(sin(x)+ 3).
 

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