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Math Help - suppose..

  1. #1
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    suppose..

    yea i don't even know where to start on this problem...

    Suppose and . Find when .

    (dx/dt)=?
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    Quote Originally Posted by tbenne3 View Post
    yea i don't even know where to start on this problem...

    Suppose and . Find when .

    (dx/dt)=?
     <br />
\frac{d}{dt}\left(xy = 3\right)<br />

     <br />
x \cdot \frac{dy}{dt} + y \cdot \frac{dx}{dt} = 0<br />

    take it from here?
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    Quote Originally Posted by skeeter View Post
     <br />
\frac{d}{dt}\left(xy = 3\right)<br />

     <br />
x \cdot \frac{dy}{dt} + y \cdot \frac{dx}{dt} = 0<br />

    take it from here?
    is it -3?
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    \frac{dx}{dt}=\frac{dx}{dy}\frac{dy}{dt}
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    Quote Originally Posted by tbenne3 View Post
    this is not that difficult.

    xy = 3

    if x = -3 , then -3y = 3 ... y = -1

    you were given \frac{dy}{dt} = -3 ... now use the derivative equation to solve for \frac{dx}{dt}
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    Quote Originally Posted by skeeter View Post
    this is not that difficult.

    xy = 3

    if x = -3 , then -3y = 3 ... y = -1

    you were given \frac{dy}{dt} = -3 ... now use the derivative equation to solve for \frac{dx}{dt}
    sorry just not following.. what is the derivative of dx/dt
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  8. #8
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     <br />
x \cdot \frac{dy}{dt} + y \cdot \frac{dx}{dt} = 0<br />

    (-3) \cdot (-3) + (-1) \cdot \frac{dx}{dt} = 0

    solve for the value of \frac{dx}{dt}
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  9. #9
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    Quote Originally Posted by skeeter View Post
     <br />
x \cdot \frac{dy}{dt} + y \cdot \frac{dx}{dt} = 0<br />

    (-3) \cdot (-3) + (-1) \cdot \frac{dx}{dt} = 0

    solve for the value of \frac{dx}{dt}
    thanks
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