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Math Help - stationary point

  1. #1
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    stationary point

    hey having a problem with the following qus.

    investigate the function f(x) = 2x - 6/(5-3x) for the nature of the stationary points (if any) and the value of the function at these points.

    i found dy/dx = 2 + 18(5-3x)^-2 make it equal to zero

    can't seem the solve for x?
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  2. #2
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    Quote Originally Posted by dadon
    hey having a problem with the following qus.

    investigate the function f(x) = 2x - 6/(5-3x) for the nature of the stationary points (if any) and the value of the function at these points.
    i found dy/dx = 2 + 18(5-3x)^-2 make it equal to zero
    can't seem the solve for x?
    Hello,

    you've made a minor mistake because you forgot to use the chain rule:

    \frac{dy}{dx} = 2 -6 \cdot (-1) \cdot (5-3x)^{-2} \cdot (-3)=2-\frac{18}{(5-3x)^2}

    Set this term equal to zero.

    Multiplying by the denominator and dividing by 2 will give:

    (5-3x)^2=9

    I'll leave this to you.

    Greetings

    EB
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  3. #3
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    thanks agian earboth
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  4. #4
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    Quote Originally Posted by dadon
    thanks agian earboth
    You are welcomed.

    EB
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