Integration Problem

  • Thread starter lost_2
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  • #1
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HI there!! i was wondering if you could help me with this..

how do you integrate -2xy/(1+x^2)?

Thank you.
 

Answers and Replies

  • #2
Hootenanny
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HI there!! i was wondering if you could help me with this..

how do you integrate -2xy/(1+x^2)?

Thank you.
Welcome to the forums,

Your question is incomplete. What are you integrating with respect to? Is y a function of x or vice versa?

As an aside, feel free to post a new topic for each new question, you don't need to tag your question on the end of others/
 
  • #3
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Hey!

Thanks for the quick reply.. Coz it a similar qns so i posted together with this. That equation is the gradient of a curve. So it's just to integrate with respect to x? How do you go about doing it?

Thank you.
 
  • #4
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Anyways this is the whole qns.

find the equation of the curve in the xy plane that passes through (1,2) and whose tangent line at a point (x,y) has a slope of -2xy/(1+x^2).
 
  • #5
Hootenanny
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Anyways this is the whole qns.

find the equation of the curve in the xy plane that passes through (1,2) and whose tangent line at a point (x,y) has a slope of -2xy/(1+x^2).
Thanks, it's always a good idea to post the entire question. So you know that,

[tex]\frac{dy}{dx} = -\frac{2xy}{1+x^2}[/tex]

Which is a first order ODE. What methods do you know for solving first order ODE's?
 
  • #6
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by using variable separable method?
 
  • #7
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is the answer y(1+x^2)= c?
 
  • #8
HallsofIvy
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You have not yet used the fact that the curve passes through (1, 2).
 

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