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Math Help - stationary points

  1. #1
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    stationary points

    I got a question to find stationary points of: y=(x^3) - 3x

    now i differentiated it and set to 0 and get

    3x^2 - 3 = 0 now am not sure from here what to do?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by taurus View Post
    I got a question to find stationary points of: y=(x^3) - 3x

    now i differentiated it and set to 0 and get

    3x^2 - 3 = 0 now am not sure from here what to do?
    solve for x of course. and then find the y coordinate for the corresponding x-values
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  3. #3
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    i did that and get 1,-2 which i dont think is right
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    Quote Originally Posted by taurus View Post
    i did that and get 1,-2 which i dont think is right
    The solutions of:

    3x^2-3=0

    are x=\pm 1

    RonL
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  5. #5
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    when i saw the answers they were:

    (-3/2, -5/4)

    ?
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    Grand Panjandrum
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    Quote Originally Posted by taurus View Post
    when i saw the answers they were:

    (-3/2, -5/4)

    ?
    If these are supposed to be the x values for which the slope of x^3-3x is
    zero then they are wrong.

    RonL
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  7. #7
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    the question is asking for the stationary points for the function:
    y = x^3 - 3x

    so the answers are wrong?
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  8. #8
    Grand Panjandrum
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    Quote Originally Posted by taurus View Post
    the question is asking for the stationary points for the function:
    y = x^3 - 3x

    so the answers are wrong?
    The posibilities are:

    1. You have copied the problem incorrectly
    2. You have checked the answer to a different question
    3. The book is wrong

    all of these are common errors

    RonL
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