- #1

lost_2

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

Thank you.

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- Thread starter lost_2
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- #1

lost_2

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

Thank you.

- #2

Hootenanny

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Science Advisor

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Welcome to the forums,

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

Thank you.

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

lost_2

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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

lost_2

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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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Thanks, it's always a good idea to post the entire question. So you know that,

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).

[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

lost_2

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by using variable separable method?

- #7

lost_2

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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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