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    A curve has the equation y=3x-x^3/2

    The curve meets the x axis at the origin and at the point A (where y is 0) and has a maximum at the point B

    i) find the x coordinate of A

    I know I need to make y 0 but I'm having such a hard time factorising it!
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    you can write

    x ( 3 - x? ) = 0

    to find ? you have to think about combining the powers of x and x? to make x3/2
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    (Original post by the bear)
    you can write

    x ( 3 - x? ) = 0

    to find ? you have to think about combining the powers of x and x? to make x3/2
    Thank you! I now have x(3-x^1/2) but I've never seen x^1/2 or the square root of x in a bracket before so I don't really know how to find x from it
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    If it is a root y=0
    Therefore x (3-x^1/2)=0
    Now if they equal zero either x=0 (the origin) or 3-x^1/2=0
    Then x^1/2=3
    Since x^1/2 is the same as square root
    You know that the square root of x=3
    From this you can find x

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    (Original post by catrinellis)
    A curve has the equation y=3x-x^3/2

    The curve meets the x axis at the origin and at the point A (where y is 0) and has a maximum at the point B

    i) find the x coordinate of A

    I know I need to make y 0 but I'm having such a hard time factorising it!
    For part ii u need to differntiate it
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    (Original post by Hanaan999)
    If x^1/2-3=0
    Then x^1/2=3
    Since x^1/2 is the same as square root
    You know that the square root of x=3
    From this you can find x

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    Ahh thank you that makes sense
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    (Original post by catrinellis)
    Thank you! I now have x(3-x^1/2) but I've never seen x^1/2 or the square root of x in a bracket before so I don't really know how to find x from it
    so you have got x ( 3 - √x ) = 0

    so either x = 0 which you were told

    or 3 - √x = 0

    so 3 = √x

    how would you continue ?
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    (Original post by the bear)
    so you have got x ( 3 - √x ) = 0

    so either x = 0 which you were told

    or 3 - √x = 0

    so 3 = √x

    how would you continue ?
    x is 9!!!
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    (Original post by catrinellis)
    x is 9!!!
    http://s2.quickmeme.com/img/40/40b96...30963ed6c7.jpg
 
 
 

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